Inkset, ink cartridge, inkjet recording method, and recorded matter

ABSTRACT

An inkset comprising at least a yellow ink composition, two types of magenta ink compositions of different color density, and a cyan ink composition:
         the magenta ink composition containing as a colorant at least one type of compound expressed by the formula M-1, and at least one type of compound expressed by the formula M-2,   the yellow ink composition containing as a colorant at least one type of compound expressed by the formula Y-1   the cyan ink composition containing as a cyan dye at least one type of compound selected from the compounds or salt thereof expressed by the formula C-1.

CROSS-REFERENCE TO RELATED APPLICATIONS

The entire disclosure of Japanese Patent Application No. 2006-337458,filed on Dec. 14, 2006, is expressly incorporated by reference herein.

BACKGROUND

1. Technical Field

The present invention relates to an inkset, and particularly to aninkset that can form an image with excellent ozonefastness,lightfastness, and humidityfastness, as well as to an ink cartridge,inkjet recording method, and recorded matter that use this inkset.

2. Related Art

In recent years attention has focused on the inkjet recording method.The inkjet recording method is a printing method where printing isperformed by spraying an ink composition as small droplets, and thesesmall droplets adhere to a recording medium such as paper or the like.This method has the characteristics of enabling high-speed printing of ahigh-resolution high quality image using a relatively inexpensivedevice. Furthermore, inkjet recording devices that use this method havewide acceptance in the market because of the excellent printing quality,low cost, relatively quiet operation, and excellent graphics capability.Of these devices, thermal (bubblejet (registered trademark)) andpiezoelectric drop on demand printers have been especially commerciallysuccessful, and are widely used as printers for personal computers atthe office and home.

Furthermore, in recent years, printed matter has been obtained byforming a color image using an inkjet recording method that uses aplurality of color ink compositions. Generally, formation of a colorimage is performed using three colors, namely a yellow ink composition,a magenta ink composition, and a cyan ink composition, or if desired,using four colors by adding a black ink composition. Furthermore, colorimages are also formed using six colors with the addition of a lightcyan ink composition and a light magenta ink composition to theaforementioned four colors, or using seven colors by also adding a darkyellow ink composition. Combinations of two or more of these inkcompositions are referred to as an inkset.

The ink compositions which are used in forming the aforementioned colorimage are required to have good coloring properties for the individualcolor of each ink composition, as well as the capability to createfavorable intermediate-colors when a plurality of ink compositions arecombined, and the recorded matter obtained thereby must not discolorwhen stored.

Furthermore, in recent years continuous improvements have been made inthe head, in the composition, recording method, and media in order toachieve “picture quality” printing using a color inkjet printer, and theimage quality obtained is similar to a photograph and at a levelindistinguishable from a “silver chloride photograph”. On the otherhand, efforts are underway to improve the storage properties of theimages of recorded matter obtained using a color inkjet printer byimproving the ink compositions and the media, and in particular thelightfastness of the image has been improved to a practical level (forexample, refer to JP-A-2000-290559 and JP-A-2001-288392). However,degradation of the image occurs not only because of the effect of light,but also because of oxidation due to oxidative gases existing in theenvironment such as ozone, and water (humidity) in the environment, andtherefore discoloration and fading of the image will proceed. Therefore,in order to further improve the storage properties of the image of therecorded matter, the ozonefastness and humidityfastness should also beimproved along with improving the lightfastness of the image formed bythe ink composition. Therefore, various investigations have beenperformed in order to improve the lightfastness, ozonefastness, andhumidityfastness of the inkjet recorded matter, but in particular,efforts to date have been made to improve the ozonefastness of thecolorants used in the ink composition (refer to International PatentW002/060994 and JP-A-2002-371214).

Furthermore, in an inkset, if the lightfastness, ozonefastness, andhumidityfastness of a specific ink composition are noticeably inferiorto the lightfastness, ozonefastness, and humidityfastness of the otherink compositions, the color formed by that specific ink composition willfade and discolor faster than the other colors, so the color balance ofthe entire image will be poor, and an observer will be aware of thedegradation in the picture quality of the image in a shorter period oftime than they could be aware of fading of an image formed by only oneink composition. Therefore, with an inkset, in addition to improving thelightfastness, ozonefastness, and humidityfastness of each of the inkcompositions which form the inkset, preferably the level of thelightfastness, ozonefastness, and humidityfastness of each of the inkcompositions, or in other words the degradation speeds and the fadingspeeds of an image formed by each of the ink compositions due to light,ozone, and water will preferably be as similar as possible. In otherwords, the lightfastness, ozonefastness, and humidityfastness of each ofthe ink compositions that make up the inkset should be excellent, andpreferably the difference in the lightfastness, ozonefastness, andhumidityfastness of each ink composition will be small.

Furthermore, images with varying color intensities can be formed and animage without a grainy feel can be obtained by using an inkjet thatincludes two different tints of ink compositions with different colorconcentrations in the same color system. An inkset that includes twotypes of ink compositions with different color concentrations in thismanner is used primarily for printing photograph images, but whenforming the photographic image, generally an ink composition with a lowcolor concentration is usually used in order to relieve or eliminate thegraininess of the image. Furthermore, when evaluating the lightfastness,ozonefastness, and humidityfastness, a pattern with an opticalconcentration near 1.0 is formed as an evaluation sample using inkcompositions with low color concentration. Therefore, in order toimprove the lightfastness, ozonefastness, and humidityfastness of theoverall inkset and the lightfastness, ozonefastness, andhumidityfastness of recorded matter with photographic images, improvingthe lightfastness, ozonefastness, and humidityfastness of the inkcompositions with low color concentration is critical. On the otherhand, ink compositions with rich color concentrations are used forprinting extremely vivid images and graphic art patterns, so improvingthe lightfastness, ozonefastness, and humidityfastness of these inkcompositions is also important.

Furthermore, a black ink composition plays an important role from theviewpoint of achieving image contrast in the image, and therefore blackink compositions are commonly included in an inkset. Therefore, when ablack ink composition is included in the inkset, the black inkcomposition must have excellent lightfastness, ozonefastness, andhumidityfastness, while at the same time the degradation speed of theblack ink composition due to light, ozone, or water must not differextremely from the degradation speed of the other ink compositions whichmake up the inkset.

As described above, in an inkset, each of the individual inkcompositions that make up the inkset must have good lightfastness,ozonefastness, and humidityfastness, while at the same time the balancebetween the lightfastness, ozonefastness, and humidityfastness of thedifferent ink compositions must be good, and when exposed to light,ozone, and water, a specific color must not fade and/or discolor fasterthan the other colors. Furthermore, a bronzing phenomenon may occur whenattempting to improve the lightfastness, ozonefastness, andhumidityfastness of each of the ink compositions which make up aninkset, and this bronzing phenomenon must also be reduced. Bronzingphenomenon refers to the phenomenon of floating red visible ink printedregions when printing is performed at high duty, and is thought to havea tendency to easily occur particularly when fill printing (printing tofill in an area at 100% duty) using an ink composition that uses a metalphthalocyanine based dye as the colorant. The bronzing phenomenonaffects the color balance of the entire image, and can lead to poorimage quality.

Furthermore, any inkset that improves the degradation of image qualityor the like and that is capable of recording and image with goodozonefastness on a recording medium, as well as an ink cartridge thatstores this inkset, a recording method that uses this inkset, andrecorded matter that is recorded using this inkset has previously beenproposed (for example, refer to JP-A-2005-105135).

While these inksets or the like provide a practical level oflightfastness and ozonefastness for consumer applications, but there isdemand for further improvement of lightfastness and ozonefastness fordiversified applications and for versatility at the edge of inkjettechnology. Furthermore, ensuring humidityfastness is an importantcharacteristic for accommodating a diversification of applicable uses.

SUMMARY

The present invention was achieved in order to resolve theaforementioned problems, and relates to an inkset that is capable offorming an image with good lightfastness and humidityfastness on arecording medium, as well as to an ink cartridge that stores thisinkset, a recording method that uses this inkset, and recorded matterthat is recorded using this inkset.

The inkset of the present invention is an inkset comprising at least ayellow ink composition, two types of magenta ink compositions ofdifferent color density, and a cyan ink composition:

the magenta ink composition containing as a colorant at least one typeof compound expressed by the following formula M-1, and at least onetype of compound expressed by the following formula M-2,

(where in formula M-1, A represents a residue of a five memberedheterocyclic diazo component A-NH₂. B¹ and B² each represent —CR¹═ or—CR²═, or either one represents a nitrogen atom while the otherrepresent either —CR¹═ or —CR²═. R⁵ and R⁶ each independently representa hydrogen atom, an aliphatic group, an aromatic group, a heterocyclicgroup, an acyl group, an alkoxycarbonyl group, an aryloxycarbonyl group,a carbamoyl group, an alkylsulfonyl group, an arylsulfonyl group, or asufamoyl group. Each group may also have a substituent group. G, R¹ andR² each independently represent a hydrogen atom, a halogen atom, analiphatic group, an aromatic group, a heterocyclic group, a cyano group,a carboxyl group, a carbamoyl group, an alkoxycarbonyl group, anaryloxycarbonyl group, an acyl group, a hydroxyl group, an alkoxy group,an aryloxy group, a silyloxy group, an acyloxy group, a carbamoyloxygroup, a heterocycloxy group, an alkoxycarbonyloxy group, anaryloxycarbonyloxy group, an amino group substituted with an alkylgroup, aryl group, or heterocyclic group, an acylamino group, a ureidogroup, a sulfamoylamino group, alkoxycarbonylamino group, anaryloxycarbonylamino group, an alkyl or arylsulfonylamino group, anaryloxycarbonylamino group, a nitro group, an alkyl or arylthio group,an alkyl or arylsulfonyl group, an alkyl or arylsulfinyl group, asulfamoyl group, a sulfo group, or a heterocyclothio group. Each groupmay also have a substituent group. Furthermore, R¹ or R⁵ or R¹ and R⁵bonded together can form a 5 or 6 membered ring.)

(where in formula M-2, M represents a hydrogen atom, ammonium group, oralkali metal atom, X represents a diaminoalkylene group, and n is either1 or 2.);

the yellow ink composition containing as a colorant at least one type ofcompound expressed by the following formula Y-1

(in the formula, X₁, X₂, Y₁, and Y₂ represent a hydrogen atom or a cyanogroup, Z₁ and Z₂ represent a substituent group with an aromatic ring, R₁and R₂ represent alkyl groups, and M represents a metal atom.);

the cyan ink composition containing as a cyan dye at least one type ofcompound selected from the group consisting of compounds or saltsthereof expressed by the following formula C-1

(wherein X₁, X₂, X₃, and X₄ in formula C-1 independently representeither —SO-Z or —SO₂-Z. Here, Z independently represents a substitutedor unsubstituted alkyl group, a substituted or unsubstituted cycloalkylgroup, a substituted or unsubstituted alkenyl group, a substituted orunsubstituted aralkyl group, a substituted or unsubstituted aryl group,or a substituted or unsubstituted heterocyclic group.

Y₁, Y₂, Y₃, and Y₄ independently represent a hydrogen atom, a halogenatom, an alkyl group, a cycloalkyl group, an alkenyl group, an aralkylgroup, an aryl group, a heterocyclic group, a cyano group, an hydroxylgroup, a nitro group, an amino group, an alkylamino group, an alkoxygroup, an aryloxy group, an amido group, an arylamino group, an ureidogroup, a sulfamoylamino group, an alkylthio group, an arylthio group, analkoxycarbonylamino group, a sulfonamide group, a carbamoyl group, analkoxycarbonyl group, a heterocycloxy group, an azo group, an acyloxygroup, a carbamoyloxy group, a silyloxy group, an aryloxycalbonyl group,an aryloxycalbonylamino group, an imido group, a heterocyclthio group, aphospholyl group, an acyl group, or an ionic hydrophilic group, and eachof the groups may also have substituent groups.

a₁ through a₄ and b₁ through b₄ represent the number of substituentgroups of X₁ through X₄ and Y₁ through Y₄. Furthermore a₁ through a₄ areindependently integers between 0 and 4, but are not all simultaneously0. b₁ through b₄ are independently integers between 0 and 4.

M represents a hydrogen atom, a metal atom or oxide, a hydroxide, or ahalide thereof.

However, at least one of X₁, X₂, X₃, X₄, Y₁, Y₂, Y₃, and Y₄ is an ionichydrophilic group or a group which has an ionic hydrophilic group as asubstituent group.).

Furthermore, with the inkset of the present invention, the compoundexpressed by formula M-1 that is preferably a colorant in the magentaink composition is a compound expressed by the following formula M-3:

(In formula M-3, R₁ through R₅ represent a hydrogen atom, alkyl group,sulfo group, or salt thereof, and when R₁ and R₅ are independently bothalkyl groups, the total number of carbons in the alkyl groups is 3 ormore, and substituent groups may also be present. X represents ahydrogen atom, an aliphatic group, an aromatic group, or a heterocyclicgroup, and Y and Z each independently represent a hydrogen atom, analiphatic group, an aromatic group, a heterocyclic group, an acyl group,an alkoxycarbonyl group, an aryloxycarbonyl group, a carbamoyl group, analkylsulfonyl group, an arylsulfonyl group, or a sulfamoyl group. Eachgroup may also have a substituent group.).

Furthermore, with the inkset of the present invention, the compoundexpressed by formula M-3 is preferably the compound expressed by thefollowing formula M-4:

(In formula M-4, R₁ through R₁₀ represent a hydrogen atom, alkyl group,sulfo group, or salt thereof, and when (R₁ and R₅) and (R₆ and R₁₀) areindependently both alkyl groups, the total number of carbons in thealkyl groups is 3 or more, and substituent groups may also be present.Furthermore, M represents a hydrogen atom or an alkali metal atom.).

Furthermore, with the inkset of the present invention, the n in thecompound expressed by the formula M-2 which is contained as a colorantin the magenta ink composition is preferably 2.

Furthermore, with the inkset of the present invention, of the two typesof magenta ink compositions of different color density, the magenta inkcomposition of lower color density preferably contains as a colorant atleast one type of compound expressed by formula M-1 and at least onetype of compound expressed by formula M-2, and the total amount of thecolorants is such that the amount of at least one type of compoundexpressed by formula M-1 is between 0.2 and 1.0 wt %, and the amount ofat least one type of compound expressed by formula M-2 is between 0.3and 1.5 wt %, based on the total weight of magenta ink composition oflower color density.

Furthermore, with the inkset of the present invention, of the two typesof magenta ink compositions of different color density, the magenta inkcomposition of higher color density preferably contains as a colorant atleast one type of compound expressed by formula M-1 and at least onetype of compound expressed by formula M-2, and the total amount of thecolorants is such that the amount of at least one type of compoundexpressed by formula M-1 is between 0.6 and 2.5 wt %, and the amount ofat least one type of compound expressed by formula M-2 is between 1.5and 7.0 wt %, based on the total weight of magenta ink composition ofhigher color density.

Furthermore, with the inkset of the present invention, of the two typesof magenta ink compositions of different color density, the contentweight ratio of the compound expressed by formula M-1 and the compoundexpressed by formula M-2 in the magenta ink composition of lower colordensity is preferably between 2:1 and 1:2.

Furthermore, with the inkset of the present invention, of the two typesof magenta ink compositions of different color density, the contentweight ratio of the compound expressed by formula M-1 and the compoundexpressed by formula M-2 in the magenta ink composition of higher colordensity is preferably between 1:1 and 1:8.

Furthermore, with the inkset of the present invention, the contentweight ratio of the compound expressed by formula M-1 and the compoundexpressed by formula M-2 in the magenta ink composition is preferablybetween 2:1 and 1:8.

Furthermore, with the inkset of the present invention, preferably themagenta ink composition further contains a betaine-based surfactantexpressed by the following b-1:

(R)p-N-[L-(COOM)q]r   (b-1)

(In formula b-1, R represents a hydrogen atom, an alkyl group, an arylgroup, or a heterocyclic group. L represents a bonding group with avalence of two or higher. M represents a hydrogen atom, an alkali metalatom, an ammonium group, a protonated organic amine or nitrogencontaining heterocyclic group, or a quaternary ammonium ion group, andrepresents a group that does not exist as a cation if M is a counter ionfor the ammonium ion containing nitrogen atom shown in formula b-1. qrepresents an integer 1 or greater, and r represent an integer between 1and 4. p represents an integer between 0 and 4, and p+r is either 3 or4. If p+r is 4, N represents a nitrogen atom that forms a quaternaryamine. If p is 2 or higher, R may be the same or may be different. If qis 2 or higher, COOM may be the same or may be different. If r is 2 orhigher, L-(COOM)_(q) may be the same or may be different.).

Furthermore, with the inkset of the present invention, the betaine-basedsurfactant expressed by formula b-1 is preferably the compound expressedby the following formula b-2:

(In formula b-2, R₁ through R₃ represent alkyl groups having 1 to 20carbons, and X represents a bonding group with a valence of 2.).

Furthermore, with the inkset of the present invention, the compoundexpressed by formula b-2 is preferably the compound expressed by thefollowing formula b-3.

Furthermore, with the inkset of the present invention, the contentweight ratio of the compound expressed by formula M-1 and thebetaine-based surfactant expressed by formula b-1 in the magenta inkcomposition is preferably between 1:3 and 3:1.

Furthermore, with the inkset of the present invention, the compoundexpressed by formula Y-1 which is contained in the yellow inkcomposition as a colorant is preferably a compound expressed by thefollowing formula Y-2:

(in the formula, X₁, X₂, Y₁, and Y₂ represent a hydrogen atom or a cyanogroup, W₁ through W₅ and W₁₁ through W₁₅ each represent a hydrogen atom,or a carboxyl group or salt thereof, M represents a metal atom, and t-Burepresent a tertiary butyl group.).

Furthermore, in the inkset of the present invention, the yellow inkcomposition preferably also contains as a colorant at least one type ofcompound expressed by the following formula Y-3:

(In the formula, R represents a methoxy group or a methyl group, and Arepresents 1,5-disulfonaphtho-3-yl or 1,5,7-trisulfonaphtho-2-yl.).

Furthermore, with the inkset of the present invention, the total amountof colorant in the yellow ink composition is preferably between 1 and 7wt % based on the total weight of yellow ink composition.

Furthermore, with the inkset of the present invention, in the compoundexpressed by formula C-1 that is contained as the cyan dye in the cyanink composition, preferably M represents a copper atom, X₁, X₂, X₃, andX₄ represent —SO₂Z, Z represents R⁵ (R⁵ represents —CH₂)₃SO₃M² where M²represents an alkali metal atom.) and/or R⁶ represents—(CH₂)₃SO₂NHCH₂CH(OH)CH₃), Y₁, Y₂, Y₃, and Y₄ are hydrogen atoms, a₁,a₂, a₃, and a₄ are either 0 or 1, two or more of a₁, a₂, a₃ and a₄ are1, and b₁, b₂, b₃, and b₄ are integers such that the sum of each of themwith the corresponding a₁, a₂, a₃, and a₄is 4.

Furthermore, with the inkset of the present invention, M² preferablyrepresents lithium.

Furthermore, with the inkset of the present invention, in the cyan dye,preferably Z in the compound expressed by formula C-1 independentlyrepresents a blend consisting of tetrasulfonates, trisulfonates, anddisulfonates selected from R⁵ or R⁶, and the molar ratio of R⁵ and R⁶contained in all of the cyan dye R⁵/R⁶ is between 2/2 and 4/0.

Furthermore, with the inkset of the present invention, at least one typeof compound selected from the group consisting of compounds or saltsthereof expressed by formula C-1 is preferably contained as a colorantin the cyan ink composition, and the total amount of colorant is between1.0 and 10 wt % based on the total weight of the cyan ink composition.

Furthermore, the inkset of the present invention has two types of cyanink compositions of different color density as the cyan ink composition,and this cyan ink composition preferably contains at least one type ofcompound selected from a group consisting of the compounds expressed byformula C-1 or salts thereof.

Furthermore, with the inkset of the present invention, of the two typesof cyan ink compositions of different color density, the cyan inkcomposition of lower color density preferably contains as a colorant atleast one type of a compound selected from a group consisting of thecompounds expressed by formula C-1 and salts thereof, and the totalamount of the colorant is between 0.4 and 3.0 wt %, based on the totalweight of the cyan ink of lower color density.

Furthermore, with the inkset of the present invention, of the two typesof cyan ink compositions of different color density, the cyan inkcomposition of higher color density preferably contains as a colorant atleast one type of a compound selected from a group consisting of thecompounds expressed by formula C-1 and salts thereof, and the totalamount of the colorant is between 2.0 and 10.0 wt %, based on the totalweight of the cyan ink of higher color density.

Furthermore, with the inkset of the present invention, in the two typesof cyan ink compositions of different color density, the ratio of theconcentration (wt %) of colorant included in the cyan ink composition oflower color density and the concentration (wt %) of colorant included inthe cyan ink composition of higher color density is preferably in arange between 1:2 and 1:8.

Furthermore, with the inkset of the present invention, both of the twotypes of cyan ink compositions of different color density contain as acolorant at least one type of compound selected from a group consistingof the compounds expressed by formula C-1 and salts thereof, and in thecompound expressed by formula C-1 that is included in the cyan inkcomposition of lower color density, Z independently represents a blendconsisting of a disulfonate, a trisulfonate, and a tetrasulfonateselected from R⁵ and R⁶, and the molar ratio of the R⁵ and R⁶ containedin all of the cyan dye R⁵/R⁶ is between 1/3 and 3/1, while in thecompound expressed by formula C-1 that is included in the cyan inkcomposition of higher color density, Z independently represents a blendconsisting of a disulfonate, a trisulfonate, and a tetrasulfonateselected from R⁵ and R⁶, and the molar ratio of the R⁵ and R⁶ containedin all of the cyan dye R⁵/R⁶ is or for a preferably between 2/2 and 4/0.

Furthermore, with the inkset of the present invention, of the two typesof cyan ink compositions of different color density, the cyan inkcomposition of lower color density further preferably contains anaromatic compound having a sulfo group as expressed by the followinggeneral formula (a) and/or (b), and/or a salt thereof:

(wherein M¹ represents a hydrogen atom, or a counter ion that forms asalt, X represents an integer of 1 or higher, R¹ and R² each represent ahydrogen atom, alkyl group having 1 to 6 carbons, or an alkoxy grouphaving 1 to 6 carbons, where R¹ and R² may be the same or different.)

(wherein M² represents a hydrogen atom, or a counter ion that forms asalt, Y represents an integer of 1 or higher, R³ and R⁴ each represent ahydrogen atom, alkyl group having 1 to 6 carbons, or an alkoxy grouphaving 1 to 6 carbons, where R³ and R⁴ may be the same or different.).

Furthermore, with the inkset of the present invention, the salt of thearomatic compound having a sulfo group expressed by general formula (a)and/or (b) is preferably a lithium salt.

Furthermore, with the inkset of the present invention, the contentweight ratio of the cyan dye and the aromatic compound having a sulfogroup and/or salt thereof in the cyan ink composition of lower colordensity is preferably in a range between 1:1 and 1:5.

Furthermore, with the inkset of the present invention, of the two typesof cyan ink compositions of different color density, the cyan inkcomposition of higher color density preferably contains at least onetype of compound selected from the group consisting of naphthalene basedaromatic compounds or salts thereof having a carboxyl group in thesecond position.

Furthermore, with the inkset of the present invention, the salt of thenaphthalene based aromatic compound having a carboxyl group in thesecond position is preferably a lithium salt.

Furthermore, the inkset of the present invention preferably alsocontains a black ink composition.

Furthermore, with the inkset of the present invention, the black inkcomposition preferably contains a colorant expressed by the followingformula Bk-1:

A₁-N═N-A₂-N═N-A₃   (Bk-1)

(in formula Bk-1, A₁ represents a substituent group expressed by thefollowing formula Bk-2 or Bk-3, A₂ represents a substituent groupexpressed by the following formula Bk-4 or Bk-5, and A3 represents asubstituent group expressed by the following formula Bk6.)

(where in formula Bk-2, M represents either lithium or sodium.).

(where in formula Bk-3, M represents either lithium or sodium.)

(where in formula Bk-6, M represents either lithium or sodium.).

Furthermore, with the inkset of the present invention, preferably theblack ink composition further contains a colorant expressed by thefollowing formula Bk-7:

(in formula Bk-7, R₁ represents a halogen atom, H, SO₃M, or COOM, R₂ andR₃ independently represent H, SO₃M, or COOM, and M represents eitherlithium or sodium. However, R₂ and R₃ are not both H.).

Furthermore, with the inkset of the present invention, the total of theamount of colorant expressed by formula Bk-1 and the amount of colorantexpressed by formula Bk-7 is preferably between 5 and 8 wt % of theblack ink composition.

Furthermore, with the inkset of the present invention, the formulationweight ratio of the colorant expressed by formula Bk-1 and the colorantexpressed by formula Bk-7 in the black ink composition is preferablybetween 2:1 and 1:2.

Furthermore, with the inkset of the present invention, preferably theblack ink composition further contains a colorant expressed by thefollowing formula Adj-1:

(where in the formula, M represents either lithium or sodium.).

Furthermore, with the inkset of the present invention, the colorantexpressed by formula Adj-1 is preferably the colorant expressed by thefollowing formula Adj-1 -1.

Furthermore, with the inkset of the present invention, preferably theblack ink composition further contains C. I. Direct Yellow 86 as acolorant.

Furthermore, with the inkset of the present invention, the inkcomposition preferably contains a nonionic surfactant.

Furthermore, with the inkset of the present invention, the nonionicsurfactant is preferably an acetylene glycol surfactant.

Furthermore, with the inkset of the present invention, the inkcomposition preferably contains between 0.1 and 5 wt % of the nonionicsurfactant.

Furthermore, with the inkset of the present invention, the inkcomposition preferably contains a penetration enhancing agent.

Furthermore, with the inkset of the present invention, the penetrationenhancing agent is preferably a glycol ether.

The ink cartridge of the present invention integrally or independentlystores the inkset.

The inkjet recording method of the present invention records uses theaforementioned inkset or the aforementioned ink cartridge.

The recorded matter of the present invention is recorded using theaforementioned inkset or the aforementioned ink cartridge.

The inkset of the present invention uses a compound expressed by formulaC-1 or salt thereof (hereinafter jointly referred to as formula C-1 dye)as a colorant of the cyan ink composition, and uses a compound expressedby formula M-1 and a compound expressed by formula M-2 as the colorantin the two types of magenta ink composition of different color density,and the compound expressed by formula Y-1 as the colorant in the yellowink composition, and therefore the ozonefastness, lightfastness, andhumidityfastness will be excellent for the image printed on recordedmatter using this inkset.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

The present inventors have constructed an inkset by combining varioustypes of ink compositions in a plurality of colors, and using thisinkset, have performed investigations to improve the ozonefastness,lightfastness, and humidityfastness. As a result, the present inventorshave discovered that if an image is recorded using an inkset thatincludes a cyan ink composition that uses a dye with the aforementionedspecific structure, two types of magenta ink composition of differentcolor density, and a yellow ink composition, the image on the recordedmatter will have excellent ozonefastness, lightfastness, andhumidityfastness, and the difference in the rate of degradation due toozone and light of an image of cyan, magenta, and yellow (as well as anyother colors formed using ink in an inkset such as black or the like ifnecessary) will be small, and therefore an inkset can be provided wheredegradation of the entire image will not easily be perceived by theobserver even if a certain amount of image degradation proceeds due toozone and light. Hereinafter, with regards to the two types of magentaink composition of different color density in the inkset of the presentinvention, the magenta ink composition of high color density will bereferred to as the “dark magenta composition”, and the magenta inkcomposition of low color density will be referred to as the “lightmagenta composition”.

Furthermore, with regards to the cyan ink composition, the presentinventors have discovered that for an inkset that includes two types ofcyan ink composition of different color density (hereinafter cyan inkcomposition of high color density will be referred to as “dark cyan inkcomposition”, and cyan ink composition of low color density will bereferred to as “light cyan ink composition”.), if a dye having theaforementioned specific structure is used as the colorant for both thedark cyan ink composition and the light cyan ink composition, and inksetwith particularly favorable ozonefastness, lightfastness, andhumidityfastness can be achieved.

Furthermore, the present inventors have discovered that the inkset ofthe present invention is preferable as an inkset used for an inkjetprinting method.

The present invention was achieved based on these findings.

The inkset according to a first aspect of the invention includes ayellow ink composition, two types of magenta ink composition ofdifferent color density, and a cyan ink composition. The cyan inkcomposition and the yellow ink composition in the first aspect of theinvention include as a colorant at least one type of compound with theaforementioned specific structures, and the two types of magenta inkcomposition of different color density each include at least one type oftwo types of compounds with a specific structure.

The inkset according to a second aspect of the invention is the inksetaccording to the first aspect, further providing at least two types ofcyan ink compositions of different color density as the cyan inkcomposition if desired, namely a dark cyan ink composition and a lightcyan ink composition, and both the dark cyan ink composition and thelight cyan ink composition preferably contain at least one type of dyewith the aforementioned specific structure as a colorant.

Furthermore, an image printed using the dark cyan ink composition thatcontains a dye of this specific structure may undergo bronzing, and inorder to suppress this phenomenon, it is preferable to also use at leastone type of compound selected from a group consisting of aromaticcompounds with a specific structure having a carboxyl group and saltsthereof.

On the other hand, the light cyan ink composition that contains a dyewith the aforementioned specific structure preferably includes at leastone type of compound selected from a group consisting of aromaticcompounds with a specific structure having a sulfone group and saltsthereof, in order to improve ozonefastness.

The inkset according to a third aspect of the invention is the inkset ofeither the first or second aspect, further containing a blackingcomposition. It is preferable that at least one type of dye selectedfrom a group consisting of dyes with the aforementioned structure beused as the black dye in the black ink composition.

The inkset of the present invention is used for a recording method thatuses an ink composition, and examples of the recording method that usean ink composition include an inkjet recording method, a recordingmethod using a writing instrument such as a pen, as well as variousother types of printing and printing methods. In particular, the inksetof the present invention preferably is an inkset that uses an inkjetprinting method.

Each of the ink compositions included in the inkset of the presentinvention will be described. First the colorants included in each of theink compositions will be described below for the ink compositions ofeach color. By using dyes which have specific chemical structures as thecolorants in ink compositions for each color in the inkset of thepresent invention, lightfastness, ozonefastness, and humidityfastness ofthe entire inkset can be achieved.

The colorant that is used in the cyan ink composition that is a part ofthe inkset of the present invention will be described. The cyan baseddye that is used as a colorant in the cyan ink composition of thepresent invention is a compound selected from the group consisting ofphthalocyanine compounds or salts thereof expressed by the followingformula C-1:

Herein, the X₁, X₂, X₃, and X₄ in formula C-1 independently representeither —SO-Z or —SO₂-Z. Here, Z independently represents a substitutedor unsubstituted alkyl group, a substituted or unsubstituted cycloalkylgroup, a substituted or unsubstituted alkenyl group, a substituted orunsubstituted aralkyl group, a substituted or unsubstituted aryl group,or a substituted or unsubstituted heterocyclic group.

Y₁, Y₂, Y₃, and Y₄ independently represent a hydrogen atom, a halogenatom, an alkyl group, a cycloalkyl group, an alkenyl group, an aralkylgroup, an aryl group, a heterocyclic group, a cyano group, an hydroxylgroup, a nitro group, an amino group, an alkylamino group, an alkoxygroup, an aryloxy group, an amido group, an arylamino group, an ureidogroup, a sulfamoylamino group, an alkylthio group, an arylthio group, analkoxycarbonylamino group, a sulfonamide group, a carbamoyl group, analkoxycarbonyl group, a heterocycloxy group, an azo group, an acyloxygroup, a carbamoyloxy group, a silyloxy group, an aryloxycalbonyl group,an aryloxycalbonylamino group, an imido group, a heterocyclthio group, aphospholyl group, an acyl group, or an ionic hydrophilic group, and eachof the groups may also have substituent groups.

a₁ through a₄ and b₁ through b₄ represent the number of substituentgroups of X₁ through X₄ and Y₁ through Y₄. Furthermore a₁ through a₄ areindependently integers between 0 and 4, but are not all simultaneously0. b₁ through b₄ are independently integers between 0 and 4.

M represents a hydrogen atom, a metal atom or oxide, a hydroxide, or ahalide thereof.

However, at least one of X₁, X₂, X₃, X₄, Y₁, Y₂, Y₃, and Y₄ is an ionichydrophilic group or a group which has an ionic hydrophilic group as asubstituent group.

In the aforementioned formula C-1 of the present invention, a₁, a₂, a₃,and a₄ are preferably either 0 or 1, two or more of a₁, a₂, a₃, and a₄are 1, and b₁, b₂, b₃, and b₄ are preferably such that the sum of eachof them with the corresponding a₁, a₂, a₃, and a₄ equals 4.

As described above, the X₁, X₂, X₃, and X₄ in the aforementioned formulaC-1 are independently represent either —SO-Z or —SO₂-Z, where Z canfurther have a substituent group, and examples of the substituent groupsthat can be on Z include a halogen atom (for example a chlorine atom ora bromine atom); a straight chain or a branched chain alkyl group having1 to 12 carbons, an aralkyl group having 7 to 18 carbons, an alkenylgroup having 2 to 12 carbons, a straight chain or branched chain alkynylgroup having 2 to 12 carbons, a cycloalkyl group having 3 to 12 carbonswhich may also have a side chain, a cycloalkenyl group having 3 to 12carbons which may also have a side chain (examples of these groupsinclude methyl, ethyl, propyl, isopropyl, t-butyl, 2-methanesulfonylethyl, 3-phenoxy propyl, trifluoromethyl, and cyclopentyl); aryl groups(such as phenyl, 4-t-butylphenyl, and 2,4-di-t-amylphenyl); heterocyclicgroups (such as imidazolyl, pirazolyl, triazolyl, 2-furyl, 2-thienyl,2-pirimidinyl, and 2-benzothiazolyl); alkyloxy groups (such as methoxy,ethoxy, 2-methoxyethoxy, and 2-methanesulfonylethoxy); aryloxy groups(such as phenoxy, 2-methylphenoxy, 4-t-butylphenoxy, 3-nitrophenoxy,3-t-butyloxycarbamoylphenoxy, and 3-methoxycarbamoyl); acylamino groups(such as acetoamido, benzamido, and4-(3-t-butyl4-hydroxyphenoxy)butaneamido); alkylamino groups (such asmethylamino, butylamino, diethylamino, and methylbutylamino); anilinogroups (such as phenylamino and 2-chloroanilino); ureido groups (such asphenylureido, methylureido, and N,N-dibutylureido); sulfamoylaminogroups (such as N,N-dipropylsulfamoylamino); alkylthio groups (such asmethylthio, octylthio, and 2-phenoxyethylthio); arylthio groups (such asphenylthio, 2-butoxy-5-t-octylphenylthio, and 2-carboxyphenylthio);alkyloxycarbonylamino groups (such as methoxycarbonylamino); sulfonamidegroups (such as methanesulfonamide, benzenesulfonamide,p-toluenesulfonamide, and octadecane);

carbamoyl groups (such as N-ethyl carbamoyl, and N,N-dibutylcarbamoyl);sulfamoyl groups (such as N-ethyl sulfamoyl, N,N-dipropylsulfamoyl, andN,N-diethylsulfamoyl); sulfonyl groups (such as methanesulfonyl,octanesulfonyl, benzenesulfonyl, and toluenesulfonyl); alkyloxycarbonylgroups (such as methoxycarbonyl and butyloxycarbonyl); heterocycloxygroups (such as 1-phenyltetrazol-5-oxy, and 2-tetrahydropiranyloxy); azogroups (such as phenylazo, 4-methoxyphenylazo, 4-pivaroylaminophenylazo,2-hydroxy-4-propanoylphenylazo); acyloxy groups (such as acetoxy);carbamoyloxy groups (such as N-methylcarbamoyloxy, andN-phenylcarbamoyloxy); silyloxy groups (such as trimethylsilyloxy, anddibutylmethylsilyloxy); aryloxycalbonylamino groups (such asphenoxycalbonylamino); imide groups (such as N-succinimide, andN-phthalimide); heterocyclothio groups (such as 2-benzothiazolylthio,2,4-di-phenoxy-1,3,5-triazole-6-thio, and 2-piridylthio); sulfinylgroups (such as 3-phenoxypropylsufinyl); phosphonyl groups (such asphenoxyphosphonyl, octyloxyphosphonyl, and phenylphosphonyl);aryloxycarbonyl groups (such as phenoxycarbonyl); acyl groups (such asacetyl, 3-phenylpropanoyl, and benzoyl); ionic hydrophilic groups (suchas carboxyl groups, sulfo groups, and quaternary ammonium groups); cyanogroups; hydroxy groups; nitro groups; and amino groups and the like.

Furthermore, the ionic hydrophilic group in formula C-1 includes sulfogroups, carboxyl groups, and quaternary ammonium groups and the like:The ionic hydrophilic group is preferably a carboxyl group or a sulfogroup, and a sulfo group is particularly preferable. The carboxyl groupand the sulfo group can be salts, and specific examples of the counterion that forms the salt include alkali metal ions (such as a sodium ion,a potassium ion, or a lithium ion) and organic cations (such as atetramethylguanidium ion).

Of the compounds expressed by formula C-1, compounds where M in formulaC-1 is a copper atom, X₁ through X₄ represent —SO₂Z, where Z representsR⁵ (R⁵ represents —(CH₂)₃SO₃M² where M² represents an alkali metalatom.) and/or R⁶ (R⁶ represents —(CH₂)₃SO₂NHCH₂CH(OH)CH₃) arepreferable, and those compounds where M² is lithium are even morepreferable. In particular, those compounds expressed by formula. C-1 arepreferably blends of tetrasulfonic acids, trisulfonic acids, anddisulfonic acids where R⁵/R⁶ (molar ratio)=3/1. These tetrasulfonicacids, trisulfonic acids, and disulfonic acids correspond to the casewhere a₁ through a₄ in formula C-1 are all equal to 1, the case whereany three of a₁ through a₄ are equal to 1 and one is equal to 0, and thecase where any two of a₁ through a₄ are equal to 1, and the other twoare equal to 0, respectively.

In particular, in the compound expressed by formula C-1 that is the cyandye, the case where M represents a copper atom, X₁, X₂, X₃, and X₄represent —SO₂Z, Z represents R⁵ (R⁵ represents —(CH₂)₃SO₃M² where M²represents an alkali metal atom.) and/or R⁶ represents(CH₂)₃SO₂NHCH₂CH(OH)CH₃), Y₁, Y₂, Y₃, and Y₄ are hydrogen atoms, a₁, a₂,a₃, and a₄ are either 0 or 1, two or more of a₁, a₂, a₃ and a₄ are 1,and b₁, b₂, b₃, and b₄ are integers such that the sum of each of themwith the corresponding a₁, a₂, a₃, and a₄ is 4 is particularlypreferable because a colorant with favorable tone (including chroma) canbe provided, while also ensuring water solubility.

In this case, if M² is lithium, the water solubility of the colorant canbe ensured, and bronzing can be avoided, so this is even morepreferable.

Furthermore, in this case, Z independently represents a blend consistingof tetrasulfonates, trisulfonates, and disulfonates selected from R⁵ orR⁶, and the molar ratio of R⁵ and R⁶ contained in all of the cyan dyeR⁵/R⁶ is between 1/3 and to 4/0, but preferably both ozonefastness andsuppression of bronzing pre achieved to a higher dimension.

The method of synthesizing the compound shown in formula C-1 will beshown below.

In the aforementioned reaction, the phthalocyanine compound expressed bygeneral formula II is one form of the compound expressed by formula C-1,and is a compound that can be used at the present invention. Thephthalocyanine compound expressed by general formula II can besynthesized by reacting a metal derivative expressed by M-(Y)d with aphthalonitrile compound expressed by general formula III and/or adiiminoisoindoline compound expressed by general formula IV. Note, ingeneral formula II, general formula III, and general formula IV, Z andZ₁ through Z₄ have the same meaning as Z in formula C-1, and M has thesame meaning as in formula C-1. Here, Y represents a monovalent ordivalent ligand such as a halogen atom, an acetate anion, anacetylacetonate, or an oxygen atom or the like, and d represents aninteger between 1 and 4. Examples of metal derivatives expressed byM-(Y)d include halides, carboxylate derivatives, sulfate, nitrate,carbonyl compounds, oxides, and complexes or the like of Al, Si, Ti, V,Mn, Fe, Co, Ni, Cu, Zn, Ge, Ru, Rh, Pd, In, Sn, Pt, and Pb. Specificexamples of these metal derivatives include copper chloride, copperbromide, copper iodide, nickel chloride, nickel bromide, nickel acetate,cobalt chloride, cobalt bromide, cobalt acetate, iron chloride, zincchloride, zinc bromide, zinc iodide, zinc acetate, vanadium chloride,vanadium oxytrichloride, palladium chloride, palladium acetate, aluminumchloride, manganese chloride, manganese acetate, acetylacetonemanganese, manganese chloride, lead chloride, lead acetate, indiumchloride, titanium chloride, and tin chloride and the like.

The compound expressed by general formula II obtained in this mannernormally is a blend of compounds expressed by the following generalformulas a-1 through a-4 which are isomers for the positions of(SO₂-Z₁), (SO₂-Z₂), (SO₂-Z₃), and (SO₂-Z₄) in general formula II (thesegroups also correspond to R₁, R₂, R₃, and R₄ in formula 1).

In the present invention, the amount of cyan based dye included in thecyan ink composition is determined by the types of X₁ through X₄ and Y₁through Y₄ in formula C-1, as well as the type of solvent component usedfor manufacturing the ink composition, but in the present invention, thetotal amount of cyan based dye (formula C-1 dye) expressed by formulaC-1 in the cyan ink composition is preferably between 1 and 10 wt %,more preferably between 2 and 6 wt % of the total amount of cyan inkcomposition. If the total amount of formula C-1 dye included in the cyanink composition is 1 wt % or higher, the chromic properties of the inkon the recording medium after printing will be favorable, and therequired image density can be achieved. Furthermore, if the total amountof C-1 dye included in the cyan ink composition is 10 wt % or lower, thedischarge properties of the cyan ink composition will be favorable whenusing the inkjet recording method, and the inkjet nozzles will noteasily become plugged, and the like.

With the inkset of the invention, a cyan ink composition of higher colordensity (hereinafter referred to as the dark cyan ink composition) and acyan ink composition of lower color density (hereinafter referred to asthe a light cyan ink composition) can be included as the cyan inkcomposition in the inkset. If the inkset of the invention includes adark cyan ink composition and a light cyan ink composition, both thedark cyan ink composition and the light cyan ink composition preferablyinclude at least one type of dye according to formula C-1 as a colorant.

As described above, if the inkset includes a dark cyan ink compositionand the lights and ink composition, the concentration of the colorant inthe light cyan ink composition can be appropriately selected in order toachieve a preferable color balance when the light cyan ink compositionis combined with the dark cyan ink composition, and is dependent on thetype of dye that is used as the colorant.

Generally, the amount of dye of formula C-1 in the light cyan inkcomposition is preferably between 0.4 and 3.0 wt % in total, based onthe total weight of light cyan ink composition. If the concentration ofthe colorant in the light cyan ink composition is 0.4 wt % or higher, adye with excellent chromogenicity can be achieved, and if theconcentration of colorant is 3.0 wt % or less, an image recorded usingthis light cyan ink composition will seem to be less grainy.

On the other hand, the total amount of dye of formula C-1 in the darksand ink composition is preferably between 2.0 and 10.0 wt %, based onthe total weight of the dark cyan ink composition, from the perspectiveof ensuring chromogenicity and ensuring the spray reliability such asresistance to plugging.

Furthermore, the ratio of the concentration (wt %) of colorant includedin the dark cyan ink composition and the concentration (wt %) ofcolorant included in the light cyan ink composition is preferably in arange between 1:2 and 1:8. By meeting these requirements, a good colorbalance can be achieved between the dark than ink composition and thelights and ink composition, and plugging of the inkjet nozzles can beprevented.

Furthermore, with the present invention, both the light and dark cyanink compositions contain as a colorant at least one type of compoundselected from a group consisting of the compounds expressed by formulaC-1 and salts thereof, and in the compound expressed by formula C-1 thatis included in the light cyan ink composition, Z independentlyrepresents a blend consisting of a disulfonate, a trisulfonate, and atetrasulfonate selected from R⁵ and R⁶, and the molar ratio of the R⁵and R⁶ contained in all of the cyan dye R⁵/R⁶ is between 1/3 and 3/1,while in the compound expressed by formula C-1 that is included in thedark cyan ink composition, Z independently represents a blend consistingof a disulfonate, a trisulfonate, and a tetrasulfonate selected from R⁵and R⁶, and the molar ratio of the R⁵ and R⁶ contained in all of thecyan dye R⁵/R⁶ is or for a preferably between 3/1 and 4/0. In this case,a good balance can be maintained between ensuring the ozonefastness andthe bronzing resistance of the light ink composition.

Furthermore, of the dark and light cyan ink compositions, the light cyanink composition preferably also contains an aromatic compound having asulfo group as expressed by the following general formula (a) and/or(b), and/or a salt thereof, in order to further enhance theozonefastness of the recorded image.

(wherein M¹ represents a hydrogen atom, or a counter ion that forms asalt, X represents an integer of 1 or higher, R¹ and R² each represent ahydrogen atom, alkyl group having 1 to 6 carbons, or an alkoxy grouphaving 1 to 6 carbons, where R¹ and R² may be the same or different.)

(wherein M² represents a hydrogen atom, or a counter ion that forms asalt, Y represents an integer of 1 or higher, R³ and R⁴ each represent ahydrogen atom, alkyl group having 1 to 6 carbons, or an alkoxy grouphaving 1 to 6 carbons, where R³ and R⁴ may be the same or different.)

In particular, the salt of the aromatic compound having a sulfo groupexpressed by general formula (a) and/or (b) is preferably a lithiumsalt, in order to avoid bronzing of the image that is obtained.

Furthermore, the content weight ratio of the cyan dye and the aromaticcompound having a sulfo group and/or salt thereof in the light cyan inkcomposition is preferably in a range between 1:1 and 1:5. If the contentis 1:1 or higher, the effect on the ozonefastness will be significant,and if the content is 1:5 or less, the reliability from plugging or thelike can easily be ensured.

The aromatic compound having a sulfo group expressed by theaforementioned general formula (a) and/or (b) and/or salt thereof can beany aromatic compound and/or salt thereof that has at least one sulfogroup in the molecular structure, but from a perspective of increasingthe ozonefastness of the image that is obtained, the aromatic compoundis preferably at least one type of compound selected from a groupconsisting of aromatic compounds which have two or more sulfo groups,specifically 1,3-benzenedisulfonic acid, naphthalene-1,5-disulfonicacid, naphthalene-1,6-disulfonic acid, naphthalene-2,6-disulfonic acid,naphthalene-2,7-disulfonic acid, and naphthalene-1,3,6-trisulfonic acidand salts thereof.

Salts of an aromatic compounds which have a sulfo group can be added inthe form of that salt and included in the ink composition, or anaromatic compound with a sulfo group and a base that can form a salt canbe added separately to the ink composition.

If the aromatic compound with a sulfo group and/or salt thereof is anaromatic compound with three or more sulfo groups and/or salt thereof,discoloration of the image due to ozone gas can be suppressed, and theresistance to discoloration of the image can be dramatically improved.

The details concerning the effect of having three or more sulfo groupsis unclear, but it is hypothesized that by a selectively using acompound that has three or more sulfo groups, the water solubility ofthe aromatic compound can be increased, and as a result, an effect ofpreventing or suppressing deposition of the aromatic compound on to thesurface of the recording media can be achieved. Therefore, the gasresistance, and especially the ozonefastness of the printed matter canbe enhanced without problems.

The aromatic compound having three or more sulfo groups and/or saltthereof can be any aromatic compound and/or salt thereof that has atleast three sulfo groups in the molecular structure, but from aperspective of increasing the ozonefastness of the image that isobtained and improving the resistance to deposition of the additive, thearomatic compound is preferably at least one type of compound selectedfrom a group consisting of naphthalene-1,3,5-trisulfonic acid,naphthalene-1,3,6-trisulfonic acid, naphthalene-1,3,7-trisulfonic acid,naphthalene-1,4,6-trisulfonic acid, and naphthalene-1,4,7-trisulfonicacid and salts thereof. Furthermore, lithium salts of the aromaticsulfonate compounds are more preferable because of the effect of alsosuppressing bronzing of the printed image.

As described above, with the cyan ink composition in the inkset of thepresent invention, or the dark cyan composition and the like cyan inkcomposition, other cyan based dyes can also be used in order to adjustthe color of the ink, to the degree that the lightfastness,ozonefastness, and humidityfastness are not severely affected.

Examples of other cyan based dyes which can be used with the presentinvention include C. I. Direct Blue 1, 10, 15, 22, 25, 55, 67, 68, 71,76, 77, 78, 80, 84, 86, 87, 90, 98, 106, 108, 109, 151, 156, 158, 159,160, 168, 189, 192, 193, 194, 199, 200, 201, 202, 203, 207, 211, 213,214, 218, 225, 229, 236, 237, 244, 248, 249, 251, 252, 264, 270, 280,288, 289, 291, C. I. Acid Blue 9, 25, 40, 41, 62, 72, 76, 78, 80, 82,92, 106, 112, 113, 120, 127:1, 129, 138, 143, 175, 181, 205, 207, 220,221, 230, 232, 247, 258, 260, 264, 271, 277, 278, 279, 280, 288, 290,326, C. I. Reactive Blue 2, 3, 5, 8, 10, 13, 14, 15, 17, 18, 19, 21, 25,26, 27, 28, 29, 38, C. I. Basic Blue 1, 3, 5, 7, 9, 22, 26, 41, 45, 46,47, 54, 57, 60, 62, 65, 66, 69, 71 and the like can be added, but thereis not a restriction to these.

With the present invention, if the concentration in the ink of thespecific colorants that are used as the cyan ink is 3 wt.% or higher,the cyan ink composition preferably contains at least one type ofcompound selected from naphthalene based aromatic compounds or saltsthereof having a carboxyl group in the second position. By adding atleast one type of compound selected from the group consisting ofnaphthalene based aromatic compounds or salts thereof having a carboxylgroup in the second position, the occurrence of bronzing phenomenon withthe cyan ink composition can be prevented. The aforementioned bronzingphenomenon is known to be a phenomenon where floating red is observed inan area where high duty printing such as fill printing is performed onspecial inkjet recording media (particularly high gloss recording media)using an ink composition which contains a cyan based dye. When thebronzing phenomenon occurs, the color balance of the entire image willbe nonuniform and the image quality will be degraded, so a favorableimage will not be obtained.

Of the naphthalene based aromatic compounds with a carboxyl group in thesecond position which are used with the present invention, alkali metalsalts of naphthalene based aromatic compounds with a carboxyl group inthe second position are particularly preferable. Of these alkali metalsalts, the use of lithium salt is particularly preferable. If lithiumsalts is used, not only can the bronzing phenomenon be prevented, butplugging of the inkjet nozzle will not easily occur.

Examples of naphthalene based aromatic compounds with a carboxyl groupin the second position or salts thereof include 2-naphthoic acid,1-hydroxy-2-naphthoic acid, 3-hydroxy-2-naphthoic acid,6-hydroxy-2-naphthoic acid, 4-hydroxybenzoic acid, 2, 6-naphthalenedicarboxylic acid, 3-methoxy-2-naphthoic acid, 3-ethoxy-2-naphthoicacid, 3-propoxy-2-naphthoic acid, 6-methoxy-2-naphthoic acid,6-ethoxy-2-naphthoic acid, and 6-propoxy-2-naphthoic acid and the like,as well as salts thereof, particularly lithium salts. 2-naphthoic acidand the lithium salt thereof are particularly preferable.

The method of adding a salt of a naphthalene based aromatic compoundwith a carboxyl group in the second position to the ink composition canbe either a method of adding the compound to the ink in the form of asalt, or a method of adding the compound to the ink composition and thenseparately adding a base that can form a salt with the naphthalene basedaromatic compound that has a carboxyl group in the second position.Furthermore, the present invention can contain at least one type ofcompound selected from the group consisting of naphthalene basedaromatic compounds or salts thereof having a carboxyl group in thesecond position.

If at least one type of compound selected from the group consisting ofnaphthalene based aromatic compounds with a carboxyl group at the secondposition or salt thereof (hereinafter referred to as naphthalene basedaromatic compound with a carboxyl group at the second position) is addedto the cyan ink composition of the inkset of the present invention, thetotal amount of naphthalene based aromatic compound having a carboxylgroup at the second position added is preferably between 0.1 and 10 wt%, more preferably between 0.5 and 5 wt % of the total amount of the inkcomposition. The suitable and preferable amount of naphthalene-basedaromatic compound having a carboxyl group in the second position or thelike included in the ink composition can be determined based on the typeof compound, the types of dyes included in the ink composition, and thetype of solvent used in the ink composition, and the like.

The ratio of the amount of cyan dye (wt %) included in the cyan inkcomposition and the amount of naphthalene based aromatic compound havinga carboxyl group in the second position (wt %) is preferably between1:0.1 and 1:10, more preferably between 1:0.3 and 1:6. If the amount ofcyan dye in the cyan ink composition is 1, occurrence of the bronzingphenomenon can be reduced if the amount of naphthalene based aromaticcarboxylic acid with a carboxyl group at the second position is greaterthan 0.1, and plugging of the inkjet nozzles can be prevented if theamount of naphthalene based aromatic compound having a carboxyl group atthe second position is less than 10.

Furthermore, in order to stabilize and dissolve the naphthalene basedaromatic compound having a carboxyl group in the second position in thecyan ink composition, the pH of the ink composition at 20° C. ispreferably 8.0 or higher. Note, the pH of the ink composition of thepresent invention is the value measured using a commercial pH meter bydirectly inserting the pH electrode into the ink composition.

Next, the colorant that is used in two types of magenta ink compositionsof different color density in the inkset of the present invention willbe described.

With the present invention, the magenta ink composition contains as acolorant at least one type of compound expressed by the followingformula M-1, and at least one type of compound expressed by thefollowing formula M-2.

In formula M-1, A represents a residue of a five membered heterocyclicdiazo component A-NH₂. B¹ and B² each represent —CR¹═ or —CR²═, oreither one represents a nitrogen atom while the other represent either—CR¹═ or —CR²═. R⁵ and R⁶ each independently represent a hydrogen atom,an aliphatic group, an aromatic group, a heterocyclic group, an acylgroup, an alkoxycarbonyl group, an aryloxycarbonyl group, a carbamoylgroup, an alkylsulfonyl group, an arylsulfonyl group, or a sufamoylgroup. Each group may also have a substituent group. G, R¹, and R² eachindependently represent a hydrogen atom, a halogen atom, an aliphaticgroup, an aromatic group, a heterocyclic group, a cyano group, acarboxyl group, a carbamoyl group, an alkoxycarbonyl group, anaryloxycarbonyl group, an acyl group, a hydroxyl group, an alkoxy group,an aryloxy group, a silyloxy group, an acyloxy group, a carbamoyloxygroup, a heterocycloxygroup, an alkoxycarbonyloxy group, anaryloxycarbonyloxy group, an amino group substituted with an alkylgroup, aryl group, or heterocyclic group, an acylamino group, a ureidogroup, a sulfamoylamino group, alkoxycarbonylamino group, anaryloxycarbonylamino group, an alkyl or arylsulfonylamino group, anaryloxycarbonylamino group, a nitro group, an alkyl or arylthio group,an alkyl or arylsulfonyl group, an alkyl or arylsulfinyl group, asulfamoyl group, a sulfo group, or a heterocyclothio group. Each groupmay also have a substituent group. Furthermore, R¹ or R⁵ or R¹ and R⁵bonded together can form a 5 or 6 membered ring.

C29

In formula M-2, M represents a hydrogen atom, ammonium group, or alkalimetal atom, X represents a diaminoalkylene group, and n is either 1 or2.

From the perspective of ensuring lightfastness and humidityfastness inparticular, the light magenta ink composition that is used in the inksetof the invention preferably contains as a colorant at least one type ofcompound expressed by formula M-1 and at least one type of compoundexpressed by formula M-2, and the total amount of the colorants is suchthat the amount of at least one type of compound expressed by formulaM-1 is between 0.2 and 1.0 wt %, and the amount of at least one type ofcompound expressed by formula M-2 is between 0.3 and 1.5 wt %, based onthe total weight of the magenta ink composition of lower color density.

From the perspective of ensuring chromogenicity, lightfastness andhumidityfastness in particular, the dark magenta ink composition that isused in the inkset of the invention preferably contains as a colorant atleast one type of compound expressed by formula M-1 and at least onetype of compound expressed by formula M-2, and the total amount of thecolorants is such that the amount of at least one type of compoundexpressed by formula M-1 is between 0.6 and 2.5 wt %, and the amount ofat least one type of compound expressed by formula M-2 is between 1.5and 7.0 wt %, based on the total weight of the magenta ink compositionof higher color density.

In the light magenta ink composition, the content weight ratio of thecompound expressed by formula M-1 and the compound expressed by formulaM-2 is preferably in a range between 2:1 and 1:2, especially from aperspective of ensuring ozonefastness and humidityfastness.

Furthermore, in the dark magenta ink composition, the content weightratio of the compound expressed by formula M-1 and the compoundexpressed by formula M-2 is preferably in a range between 1:1 and 1:8,especially from a perspective of ensuring ozonefastness andhumidityfastness.

The magenta ink composition used in the inkset of the present inventioncontains as a colorant at least one type of compound expressed byformula M-1 and at least one type of compound expressed by formula M-2in an aqueous medium consisting of water and water-soluble organicsolvents, and if necessary, can also contain a moisture retaining agent,a surfactant, a penetration enhancer, a viscosity adjusting agent, a pHadjusting agent, and other additives. By jointly using the compoundexpressed by formula M-1 and the compound expressed by formula M-2, anink composition can be provided that has excellent lightfastness,ozonefastness, and humidityfastness, and that also has balancedproperties.

The preferable form of the magenta ink composition is an ink compositionthat provides enhanced stability, humidityfastness, lightfastness, andozonefastness to the recorded matter of the colorant, by adding asadditives the betaine-based surfactant expressed by formulas b-1 throughb-3, an antifoaming agent, and aromatic compound containing a carboxylgroup, a urea derivative, a nonionic surfactant, and a penetrationenhancer, added either independently or as a combination of two or more.

The compound expressed by formula M-1 that is used in the presentinvention (magenta dye) can be one type used independently or aplurality of types used in combination.

The compound expressed by formula M-1 is preferably the compoundexpressed by formula M-3.

In formula M-3, R₁ through R₅ represent a hydrogen atom, an alkyl group,a sulfo group, or a salt thereof. When R₁ and R₅ in formula M-3 areindependently both alkyl groups, the total number of carbons in thealkyl groups is 3 or more, and substituent groups may also be present. Xrepresents a hydrogen atom, an aliphatic group, an aromatic group, or aheterocyclic group, and Y and Z each independently represent a hydrogenatom, an aliphatic group, an aromatic group, a heterocyclic group, anacyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, acarbamoyl group, an alkylsulfonyl group, an arylsulfonyl group, or asulfamoyl group. Each group may also have a substituent group.Furthermore, if a sulfo group is included in R₁ through R₅, the form is—SO₃M. In this case, M is preferably an alkali metal atom, and morepreferably is either lithium or sodium.

Of those compounds expressed by formula M-3, compounds expressed byformula M-4 are preferable for having excellent lightfastness andozonefastness and improved humidityfastness toward betaine-basedsurfactants as will be discussed later.

(In formula M-4, R₁ through R₁₀ represent a hydrogen atom, alkyl group,sulfo group, or salt thereof, and when (R₁ and R₅) and (R₆ and R₁₀) areindependently both alkyl groups, the total number of carbons in thealkyl groups is 3 or more, and substituent groups may also be present.Furthermore, M represents a hydrogen atom or an alkali metal atom.)

When the compound expressed by formula M-1 added as a colorant to themagenta ink composition is used together with the compound expressed byformula M-2 (magenta based dye), M represents a hydrogen atom, or anammonium group or alkali metal atom that forms a salt, X represents adiaminoalkylene group, and n is either 1 or 2.

The addition of the compound expressed by general formula M-2 has aparticularly strong effect at improving the humidityfastness. Thecompound expressed by general formula M-2 can be a single type usedindependently or a plurality of types may be used together. Of thesecompounds expressed by general formula M-2, compounds which have aconstruction where n equals 2 will have a favorable humidityfastness,and are particularly preferable.

Furthermore, other magenta based dyes can be jointly used in the magentaink composition in order to adjust the color or the like to the degreethat the various properties such as lightfastness are not significantlydegraded.

Examples of magenta based dyes other than compounds expressed by formulaM-1 and formula M-2 include C. I. Direct Red 2, 4, 9, 23, 26, 31, 39,62, 63, 72, 75, 76, 79, 80, 81, 83, 84, 89, 92, 95, 111, 173, 184, 207,211, 212, 214, 218, 221, 223, 224, 225, 226, 227, 232, 233, 240, 241,242, 243, 247, C. I. Direct Violet 7, 9, 47, 48, 51, 66, 90, 93, 94, 95,98, 100, 101, C. I. Acid Red 35, 42, 52, 57, 62, 80, 82, 111, 114, 118,119, 127, 128, 131, 143, 151, 154, 158, 249, 254, 257, 261, 263, 266,289, 299, 301, 305, 336, 337, 361, 396, 397, C.I. Acid Violet 5, 34, 43,47, 48, 90, 103, 126, C. I. Reactive Red 3, 13, 17, 19, 21, 22, 23, 24,29, 35, 37, 40, 41, 43, 45, 49, 55, C. I. Reactive Violet, 1, 3, 4, 5,6, 7, 8, 9, 16, 17, 22, 23, 24, 26, 27, 33, 34, C. I. Basic Red 12, 13,14, 15, 18, 22, 23, 24, 25, 27, 29, 35, 36, 38, 39, 45, 46, C. I. BasicViolet 1, 2, 3, 7, 10, 15, 16, 20, 21, 25, 27, 28, 35, 37, 39, 40, 48and the like.

In the magenta ink composition containing a compound expressed byformula M-1 and a compound expressed by formula M-2 as colorants, theadhesion of the colorant to the recording media can be dramaticallyimproved by adding the betaine-based surfactant expressed by formulab-1, while at the same time the humidityfastness will be improved, thelightfastness and ozonefastness will also be improved, and the recordedmatter will be able to maintain a stable image for long period of time.

In formula b-1, R represents a hydrogen atom, an alkyl group, an arylgroup, or a heterocyclic group. L represents a bonding group with avalence of two or higher. M represents a hydrogen atom, an alkali metalatom, an ammonium group, a protonated organic amine or nitrogencontaining heterocyclic group, or a quaternary ammonium ion group, andrepresents a group that does not exist as a cation if M is a counter ionfor the ammonium ion containing nitrogen atom shown in formula b-1. qrepresents an integer 1 or greater, and r represent an integer between 1and 4. p represents an integer between 0 and 4, and p+r is either 3 or4. If p+r is 4, N represents a nitrogen atom that forms a quaternaryamine. If p is 2 or higher, R may be the same or may be different. If qis 2 or higher, COOM may be the same or may be different. If r is 2 orhigher, L-(COOM)_(q) may be the same or may be different.

Of the betaine-based surfactants expressed by formula b-1, thosebetaine-based surfactants expressed by formula b-2 are preferable fromthe viewpoint of increased adhesion of the ink composition to therecording media. In formula b-2, R₁ through R₃ represent alkyl groupshaving 1 to 20 carbons, and X represents a bonding group with a valenceof 2. In particular, those betaine-based surfactants expressed byformula b-3 are highly preferable for the effect of increased adhesionof the ink composition to the recording media. The betaine-basedsurfactant expressed by general formula b-1 can be a single type usedindependently or a plurality of types may be blended and used together.

The effect of adding the betaine-based surfactant expressed by formulab-1 is primarily to suppress a reduction in the humidityfastness causedby the compound expressed by formula M-1, and to improve the adhesion ofthe colorants to the recording media, and the content weight ratio ofthe compound expressed by formula M-1 and the betaine-based surfactantexpressed by formula b-1 is preferably in a range between 1:3 and 3:1,and more preferably in a range between 1:2 and 2:1. By maintaining thecontent weight ratio of the compound expressed by formula M-1 and thebetaine-based surfactant within this range, the adhesion of the colorantto the recording media can be dramatically improved.

As described above, the betaine-based surfactant expressed by formulab-1 has a characteristic improving effect on the ink composition, and inparticular has the effect of improving adhesion dramatically, but alsocauses foaming, and depending on the amount added and combinations withother additives, foaming of the ink composition may increase, the loadon the ink system will increase, and the expense of building the systemmay increase.

Therefore, when a betaine-based surfactant with the aforementionedconstruction is added, specific antifoaming agents are preferably added.

In the magenta in composition, an antifoaming agent is used inconjunction with the betaine-based surfactant, and is preferably analiphatic diol compound having 4 to 6 carbons and 2 hydroxyl groups, ora diacetylene tetraol based compound.

Examples of the aliphatic diol compound which has between 4 and 6carbons and 2 hydroxyl groups include 1,4-butanediol, 1,5-pentanediol,1,2-hexanediol, 1,6-hexanediol, and the like, but of these,1,2-hexanediol is preferable. Furthermore, the diacetylene tetraol basedcompound can be procured as a commercial product, and examples includeSurfinol MD 20 and the like manufactured by Air Products Inc.

If the amount of the antifoaming agent added is too low, the antifoamingeffect on the ink composition will be insufficient, but if too high, theprinting quality and storage stability will be negatively affected.Therefore, the content in the ink composition of the present inventionpreferably between 0.05 and 10.0 wt %, and more preferably between 0.1and 5.0 wt %.

Furthermore, by maintaining the content weight ratio of the antifoamingagent to the betaine-based surfactant expressed by formula b-1 to arange between 1:10 and 4: 1, an ink composition will be obtained whichhas a good balance between having excellent printing stability andexcellent antifoaming effects and foam suppressing effects.

With the present invention, at least one type of compound selected fromaromatic compounds with a carboxyl group or salt thereof is used inorder to improve the humidityfastness and improve the adhesion of thecolorant to the recording media. Any aromatic compound with at least onecarboxyl group in the molecular structure can be used, but compoundswith only one carboxyl group are preferable, and those with anaphthalene backbone are particularly preferable. Furthermore, compoundswhich have a naphthalene backbone and have a carboxyl group in thesecond position as well as salts thereof are more preferable, and alkalimetal salts of compounds which have a naphthalene backbone and acarboxyl group at the second position are especially preferable. Ofthose alkali metal salts of compounds which have a naphthalene backboneand a carboxyl group in the second position, lithium salts arepreferable for resisting plugging.

Specific examples of aromatic compounds with a carboxyl group or saltsthereof include 2-hydroxy-1-naphthoic acid, 1-hydroxy-2-naphthoic acid,1-naphthoic acid, 2-naphthoic acid, 3-hydroxy-2-naphthoic acid,6-hydroxy-2-naphthoic acid, 3-methoxy-2-naphthoic acid,6-methoxy-2-naphthoic acid, 6-ethoxy-2-naphthoic acid,6-propoxy-2-naphthoic acid, and 4-hydroxybenzoic acid, and2,6-naphthalene dicarboxylic acid and the like, as well as saltsthereof, and particularly lithium salts.

Salts of an aromatic compounds which have a carboxyl group can be addedin the form of a salt and included in the ink, or an aromatic compoundwith a carboxylic group and a base can be added separately to the ink.

The formulation amount of at least one compound selected from aromaticcompounds having a carboxyl group or salt thereof is determined by a thetype of aromatic compound having a carboxyl group and/or salt thereof,the type of colorants, the type of solvent component, and the otheradditives and the like, but the amount is preferably between 0.1 and 10wt % based on the total weight of the ink composition, and preferably ina range between 0.5 and 5 wt %.

Furthermore, the content weight ratio between the compound expressed byformula M-1 and the at least one type of compound selected from anaromatic compound having a carboxyl group or salt thereof preferably ina range between 5:1 and 1:3, and more preferably in a range between 3:1and 1:2. If the aforementioned content ratio is higher than 5:1, theeffect of improving the humidityfastness can be sufficiently achieved,and if the ratio is below 1:3, the plugging resistance (pluggingreliability) can easily be ensured.

Adding a urea derivative to the magenta ink composition has the effectof enhancing the lightfastness.

Examples of the urea derivative that can be used with the presentinvention include urea, aryl urea, dimethylol urea, malonyl urea,carbamyl urea, n-butyl urea, dibutyl urea, N,N-dimethyl urea,1,3-dimethyl urea, N-methyl urea, hydroxyurea, ethyl urea, methyl urea,creatinine, 2-imidazolidinone, benzyl urea, (R)-(+)-1-phenylethyl urea,phenyl urea, 3-hydroxyphenyl urea, 1-phenylsemicarbazide,4-phenylsemicarbazide, N-benzoyl urea, and N,N′-O-phenylene urea, andthe like, and these compounds can be used independently or can be usedas a combination of two or more types.

The amount of the urea derivative is preferably in a range between 0.5and 20 wt %, more preferably in a range between 1 and 16 wt %, and evenmore preferably in a range between 2 and 12 wt %, based on the totalweight of the ink composition. The effect of improving the likeresistance by adding a urea derivative can be clearly seen if the amountadded is 0.5 wt % or higher, and good reliability with regards toplugging or the like can be maintained if the amount added is 20 wt % orless.

In the magenta ink composition, the content weight ratio of thecompounds expressed by formulas M-1 and M-2 and the urea derivative ispreferably in a range between 5:1 and 1 :10, more preferably in a rangebetween 4:1 and 1:8, and even more preferably in a range between 3:1 and1:5. By maintaining the ratio of both components in this range, theproperties of increased lightfastness and enhanced reliability can beachieved to a higher dimension.

In order to stabilize and dissolve the aforementioned colorant,betaine-based surfactant, aromatic compound having a carboxyl group, andurea derivative and the like, the pH (20° C.) of the ink composition ispreferably at 8.0 or higher. Furthermore, when the compatibility withthe materials is considered when the ink composition contacts withvarious types of materials, the pH of the ink composition is preferably10.5 or lower. In order to better achieve both properties, the pH of theink composition is more preferably adjusted to between 8.5 and 10.0.

Next, the colorant that is used in the yellow ink composition that is apart of the inkset of the present invention will be described.

In the inkset of the present invention, the yellow ink compositioncontains as a colorant at least one type of compound expressed by thefollowing formula Y-1.

(In the formula, X₁, X₂, Y₁, and Y₂ represent a hydrogen atom or a cyanogroup, Z₁ and Z₂ represent a substituent group with an aromatic ring, R₁and R₂ represent alkyl groups, and M is a metal atom)

In particular, the compound expressed by formula Y-1 is preferably thecompound expressed by formula Y-2, from the viewpoint of improvedlightfastness and ozonefastness.

(in the formula, X₁, X₂, Y₁, and Y₂ represent a hydrogen atom or a cyanogroup, W₁ through W₅ and W₁₁ through W₁₅ each represent a hydrogen atom,or a carboxyl group or salt thereof, M represents a metal atom, and t-Burepresent a tertiary butyl group.)

The yellow ink composition preferably contains at least one type ofcompound expressed by formula Y-3 as a colorant, in order to havesimilar ozonefastness as the magenta ink composition and the cyan inkcomposition.

(In the formula, R represents a methoxy group or a methyl group, and Arepresents 1,5-disulfonaphtho-3-yl or 1,5,7-trisulfonaphtho-2-yl.)

Furthermore, with the present invention, other yellow based dyes canalso be used in order to adjust the color of the yellow ink composition,to the degree that the ozonefastness, lightfastness, andhumidityfastness are not severely affected.

With the present invention, the concentration of color and included inthe yellow ink composition can be suitably selected based on the colorvalue of the compound (dye) used as the colorant, but the total amountof colorant in the yellow ink composition is preferably between 1.0 and7.0 wt % based on the total weight of the yellow ink composition. Goodchromic properties can be obtained if the concentration of the totalamount of colorants included in the yellow ink composition is 1.0 wt %or higher, and characteristics such as nozzle spraying properties arethe like which are required for the ink composition to be used with theinkjet recording method will be favorable and plugging of the ink nozzlecan be prevented if the concentration of the total amount of colorant is7.0 wt % or less.

Next, the colorant that is used in the black ink composition that is apart of the inkset of the present invention will be described.

The inkset of the present invention can also contain a black inkcomposition if desired. By including a black ink composition in theinkset of the present invention, an image with favorable contrast can beformed on the recording media.

The black ink composition contains a colorant expressed by the followingformula Bk-1 and if necessary, can also contain a surfactant, apermeation promoter, and other additives. Furthermore, the color andexpressed by formula Bk-1 can be used independently, or two or moretypes can be blended and used together.

C35

A₁-N═N-A₂-N═N-A₃   (Bk-1)

(in formula Bk-1, A₁ represents a substituent group expressed by thefollowing formula Bk-2 or Bk-3, A₂ represents a substituent groupexpressed by the following formula Bk-4 or Bk-5, and A₃ represents asubstituent group expressed by the following formula Bk-6)

(where in formula Bk-2, M represents either lithium or sodium.)

(where in formula Bk-3, M represents either lithium or sodium.)

(where in formula Bk-6, M represents either lithium or sodium.)

Specific examples of colorants expressed by formula Bk-1 include thecolorants shown by the following formula Bk-1-1, formula Bk-1-2, formulaBk-1-3, and formula Bk-1 4 which are combinations where A₁ through A₃ informula Bk-1 are as shown in Table 1. One of these colorants can be usedindependently, or two or more types can be blended and used together.

TABLE 1 A₁ A₂ A₃ FORMULABk-1-1

FORMULABk-1-2

FORMULABk-1-3

FORMULABk-1-4

In Table 1, M represents lithium or sodium.

Preferably, the black ink composition further contains a colorantexpressed by formula Bk-7, in order to improve the chromic properties(optical density) on a nonglossy media (matte paper or regular paper).The colorant expressed by formula Bk-7 can be used independently, or twoor more types can be blended and used together.

(in formula Bk-7, R₁ represents a halogen atom, H, SO₃M, or COOM, R₂ andR₃ independently represent H, SO₃M, or COOM, and M represents eitherlithium or sodium. However, R₂ and R₃ are not both H.)

Specific examples of colorants expressed by formula. Bk-7 include thecolorants shown by the following formula Bk-7-1, formula Bk-7-2, andformula Bk-7-3. One of these colorants can be used independently, or twoor more types can be blended and used together.

(in formula Bk-7-1, M represents either lithium or sodium. However, notall cases of M are sodium.)

(in formula Bk-7-2, M represents either lithium or sodium. However, notall cases of M are sodium.)

(in formula Bk-7-3, M represents either lithium or sodium. However, allcases of M are not sodium.)

If the colorant expressed by formula Bk-1 and the colorant expressed byformula Bk-7 are used in combination, the formulation weight ratio ofthe colorant expressed by formula Bk-1 and the colorant expressed byformula Bk-7 is not particularly restricted, but is preferably between2:1 and 1:2. Furthermore, if the formulation weight ratio of thecolorant expressed by formula Bk-1 is too high, the colors on a mattepaper may be inferior, but if the formulation weight ratio of thecolorant expressed by formula Bk-7 is too high, ozonefastness may beinferior, and bronzing phenomenon can easily occur.

Furthermore, the total of the amount of colorant expressed by formulaBk-1 and the amount of colorant expressed by formula Bk-7 in the blackink composition is preferably between 5 and 8 wt %, and particularlybetween 5 and 7 wt %. Within this range, the chromic properties of therecorded image can be ensured, while the occurrence of bronzingphenomenon can be suppressed.

Furthermore, if a colorant expressed by formula Adj-1 is added, theblack ink composition will have an effect of suppressing bronzingphenomenon, and a black ink composition with a tone approachingachromatic color even at intermediate duty can be achieved.

(where in formula Adj-1, M represents either lithium or sodium.)

Specific examples of the colorants expressed by formula Adj-1 includethe colorants shown by the following formula Adj-1-1 and formulaAdj-1-2.

The weight ratio between the total formulation amount of colorantexpressed by formula Bk-1 and colorant expressed by formula Bk-7 to theformulation amount of colorant expressed by formula Adj-1 is preferablyin a range between 4:1 and 7:1 from the viewpoint of ensuring colortone.

Furthermore, by adding C. I. Direct Yellow 86 in addition to thecolorant expressed by formula Adj-1, achieving a tone that approaches anachromatic color can be made easier and even more precise color tuningcan be achieved as compared to when only the colorant expressed byformula Adj-1 is added.

The weight ratio between the total formulation amount of colorantexpressed by formula Bk-1 and colorant expressed by formula Bk-7 to thetotal formulation amount of colorant expressed by formula Adj-1 and C.I. Direct Yellow 86 is preferably in a range between 3:1 and 5:1 fromthe viewpoint of ensuring color tone.

The colorants used in each of the ink compositions in the inkset of thepresent invention and the amount of colorants in the ink compositionswas described above, but other components which are included in each ofthe ink compositions will be described below.

Each of the ink compositions of the present invention can be obtained bydissolving the aforementioned colorants (dyes) in an appropriatesolvent. The solvent for dissolving the colorants in each of theaforementioned ink compositions preferably uses water or a blend ofwater and a water soluble organic solvent as the main solvent. The watercan be ion exchange water, ultra filtration water, reverse osmosiswater, or distilled water or the like. Furthermore, using water whichhas been chemically sterilized by ultraviolet light irradiation or theaddition of hydrogen peroxide is preferable from the viewpoint oflong-term storage. The amount of water in each of the ink compositionsthat make up the inkset of the present invention is preferably in arange between 40 and 90 wt %, and more preferably in a range between 50and 80 wt %.

As described above, each of the ink compositions of the presentinvention can use water and a water soluble organic solvent as a solventmedium. The water-soluble organic solvent is preferably a solvent thatis capable of dissolving the dye, and preferably has a lower vaporpressure than pure water.

The water-soluble organic solvent that is used with the presentinvention is preferably ethylene glycol, propylene glycol, butanediol,pentanediol, 2-butene-1,4-diol, 2-methyl-2,4-pentanediol, glycerin,1,2,6-hexanetriol, diethylene glycol, triethylene glycol, dipropyleneglycol, and other polyhydric alcohols, acetonylacetone and otherketones, γ-butylolactone, triethyl phosphate and other esters, furfurylalcohol, tetrahydrofurfuryl alcohol, or thiodiglycol or the like, butthere is no restriction to these. By using water and a water solubleorganic solvent as the solvent medium in the ink composition, thestability of discharging ink composition from the ink head can beimproved, and the viscosity of the ink composition can easily beadjusted downward or the like while having almost no impact on othercharacteristics.

Furthermore, at least one type of moisture retaining agent selected froma sugar can be included in each of the ink compositions of the presentinvention. By including a moisture retaining agent in the inkcomposition, evaporation of the water content from the ink can besuppressed and the ink will be able to retain moisture when the inkcomposition is used with the inkjet recording method. The sugar which isused with the present invention is preferably maltitol, sorbitol,gluconolactone, or maltose or the like. Note, the aforementioned watersoluble organic solvent also acts as a moisture retaining agent.

The total amount of water-soluble organic solvent and/or moistureretaining agent in the ink composition is preferably between 5 and 50 wt%, more preferably between 5 and 30 wt %, and even more preferablybetween 5 and 20 wt %. If the amounts thereof is 5 wt % or higher, andink with good moisture retaining properties can be obtained, and if theamount is 50 wt % or less, the viscosity of the ink composition can beadjusted to a viscosity that is preferable for use with an inkjetrecording method.

Other preferable additives which are added to the ink compositions thatcompose the inkset of the present invention will be described below.

The ink compositions that compose the inkset of the present inventionpreferably contain a nonionic surfactant. By adding a nonionicsurfactant, the permeability of the ink composition into the recordingmedia will be excellent, and during printing, the ink composition willquickly adhere to the recording media. Furthermore, each dot that isrecorded by the ink composition on the recording media is preferably asround as possible, and the effects of increasing the roundness of theimage formed by a single dot and improving the quality of the imageobtained can be achieved if a nonionic surfactant is included in the inkcomposition.

The nonionic surfactant that can be used with the present invention ispreferably an acetylene glycol based surfactant, but this is not arestriction. The acetylene glycol based surfactant that is used in theink compositions of the present invention is preferably a compoundexpressed by the following formula a-1:

(in formula a-1, R¹, R², R³, and R⁴ represents a straight chain, cyclic,or branched chain alkyl chain having 1 to 6 carbons, and A¹O and A²Oeach independently represent an oxyalkylene chain having 2 to 3 carbons,such as oxyethylene or oxypropylene, or a polyoxyalkylene chain obtainedby polymerizing or copolymerizing alkylene oxides having 2 to 3 carbons,such as a polyoxyethylene chain, a polyoxypropylene chain, or apolyoxyethylenepropylene chain. Furthermore, in the formula, n and mrepresent the number of units of A¹O or A²O, or in other words thenumber of repeating oxyalkylene units, and are numbers that meet theconditions of 0≦n<30, 0≦m30, and 0≦n+m<50.)

Examples of the acetylene glycol based surfactant include Surfinol 465(trademark), Surfinol 104 (trademark) (product trade names, manufacturedby Air Products and Chemicals Inc.), Olfin PD001 (trademark), OlfinE1010 (trademark) (product trade names, manufactured by Nissin ChemicalIndustry Co., Ltd.), and at least one type of surfactant selectedtherefrom is preferably added to the ink compositions that compose theinkset of the present invention.

With the present invention, the nonionic surfactant in the inkcompositions should be added such that the amount of nonionic surfactantin the ink composition is preferably between 0.1 and 5 wt %, and morepreferably between 0.5 and 2 wt %. By adding 0.1 wt % or more of anonionic surfactant to the ink compositions, the permeability of each ofthe ink compositions into the recording media can be increased. Byadding 5 wt % or less of the nonionic surfactant to the inkcompositions, bleeding of the image formed by the ink composition on therecording media can be suppressed.

Furthermore, by adding a glycol ether as a permeation enhancing agent tothe ink composition in addition to the nonionic surfactant, permeationof the ink composition into the recording medium can be enhanced, whileat the same time, bleeding of ink at the interface between adjacentcolor inks during color printing can be reduced and a very vivid imagecan be obtained. Therefore, a permeation enhancing agent is preferablyadded to the ink compositions that compose the inkset of the presentinvention.

Examples of the aforementioned glycol ethers which are preferably usedas a permeation enhancing agent include ethylene glycol monobutyl ether,diethylene glycol monobutyl ether, triethylene glycol monoethyl ether,propylene glycol monomethyl ether, dipropylene glycol monoethyl ether,propylene glycol monobutyl ether, dipropylene glycol monobutyl ether,triethylene glycol monobutyl ether, and the like, but there is norestriction to these. The amount of these glycol ethers in the inkcomposition is preferably between 3 and 30 wt %, and more preferablybetween 5 and 15 wt %. By adding 3 wt % or more of a glycol ether,bleeding between adjacent inks during color printing can effectively beprevented, and by adding 30 wt % or less, smearing of the image caneasily be prevented, and the storage stability of the ink can beimproved.

Furthermore, other materials selected from a pH adjusting agent such astriethanolamine or an alkali metal hydroxide, water-soluble polymer suchas sodium alginate, a water soluble resin, a fluoride based surfactant,a preservative, an antifungal agent, a rust inhibitor, a dissolving aid,an antioxidant, and an ultraviolet light absorber and the like can alsobe added if desired to the ink composition of the present invention.These components can be used individually, or as a blend of two or more.Furthermore, these components do not need to be added if there is noneed. A person skilled in the art can use a preferred amount of aselected additive to the extent that the effect of the present inventionis not hindered. Note, the aforementioned dissolving aid is an additivefor dissolving insoluble materials and maintaining the ink compositionin a uniform solution, when an insoluble material is deposited from theink composition.

Examples of the dissolving aid include N-methyl-2-pyrrolidone,2-pyrrolidone and other pyrrolidones, urea, thiourea, tetramethyl urea,and other ureas, allophanate, methylallophanate and other allophanates,biuret, dimethylbiuret, tetramethylbiuret, and other biurets, and thelike, but the present invention is not restricted to these. Furthermore,an example of the aforementioned antioxidants includes L-ascorbic acidor salt thereof, but there is no restriction to these.

Examples of the aforementioned preservatives and antifungal agentsinclude sodium benzoate, sodium pentachlorophenol, sodium2-pyridinethiol-1-oxide, sodium sorbitate, sodium dehyroacetate, and1,2-dibenzothiazoline-3-one (Proxel CRL, Proxel BDN, Proxel GXL, ProxelXL-2, and Proxel TN (all product names) manufactured by AVECIABiologics, Ltd.), and the like, but there is no restriction to these.

Examples of the aforementioned pH adjusting agent include amines andderivatives thereof such as diethanolamine, triethanolamine,propanolamine, and morpholine; metal hydroxides such as potassiumhydroxide, sodium hydroxide, and lithium hydroxide; ammonium salts suchas ammonium hydroxide, quaternary ammonium hydroxide (such astetramethyl ammonium and the like); carbonates such as potassiumcarbonate, sodium carbonate, and lithium carbonate; as well as otherphosphates and the like, but there is no restriction to these.

The inkset compositions that compose the inkset of the present inventionare prepared using appropriately selected components from theaforementioned components, and the viscosity of the ink compositionobtained is preferably less than 10 mPa·s at 20° C. Furthermore, withthe present invention, the surface tension of the ink composition ispreferably 45 mN/m or less at 20° C., and a range between 25 and 45 mN/mis particularly preferable. By adjusting the viscosity and the surfacetension in this manner, an ink composition with favorable properties foruse with an ink jet recording method can be obtained. Adjusting theviscosity and the surface tension can be performed by appropriatelyselecting and adjusting the amount of solvent and the amount of eachtype of additive included in the ink composition, as well as the typesof additives and solvents and the like which are added.

Note, the ink compositions which compose the inkset of the presentinvention preferably have a pH at 20° C. that is between 7.0 and 10.5,more preferably between 7.5 and 10.0. By maintaining the pH of the inkcomposition at 20° C. at 7.0 or higher, peeling of the platingcodeposited on the inkjet head can be prevented, and the spraycharacteristics of the ink composition from the inkjet head can bestabilized. Furthermore, by maintaining the pH of the ink composition at20° C. at 10.5 or lower, degradation of the various types of materialsthat contact with the ink composition such as the materials that make upthe ink cartridge and the inkjet head, can be prevented.

The method of preparing the ink composition of the present invention isfor example a method of sufficiently blending the various types ofcomponents that will be included in the ink composition, and dissolvingto be as uniform as possible, and then pressure filtering using amembrane filter with a pore size of 0.8 μm, and then degassing thesolution obtained using a vacuum pump, but this is not a restriction.

Next, the inkset of the present invention containing the aforementionedink compositions can be used in an ink cartridge that integrally orindependently stores the inkset, and this is preferable from theviewpoint of handling convenience. The ink cartridge that contains theinkset is commonly known in this field of technology, and the inkcartridge can be made by appropriately using commonly known methods.

The inkset and the ink cartridge of the present invention can be usedfor general writing tools, recorders, and pen plotters and the like, butis most preferably used with an inkjet recording method. The inkjetrecording method that can use the inkset or ink cartridge of the presentinvention also includes any recording method where the ink compositionis sprayed as liquid droplets from a fine nozzle, and the liquiddroplets are made to adhere to the recording media. Specific examples ofinkjet recording methods that can use the ink composition of the presentinvention will be described below.

The first method is a method known as the electrostatic suction method.The electrostatic section method is a method of recording an image byapplying an electric field between a nozzle and an accelerationelectrode located to the front of the nozzle, continuously sprayingliquid droplets of ink from the nozzle, and applying a printinginformation signal to a deflecting electrode while the ink droplets arepassing between the deflecting electrode, and thereby the ink dropletswill travel toward the recording media and the inch will adhere to therecording media, or a method where the ink droplets are sprayed from anozzle toward the recording media according to a print informationsignal without deflecting the ink droplets. The inkset or ink cartridgeof the present invention is preferably used with the electrostaticsuction recording method.

A second method is a method of forcefully spraying ink droplets from aninkjet nozzle by mechanically vibrating the nozzle using a water crystaloscillator while applying pressure on the ink solution using a smallpump. The ink droplets sprayed from the nozzle are electrically chargedwhile being sprayed, and a printing information signal is provided to adeflecting electrode while the ink droplets pass between the deflectingelectrodes, and thereby an image is recorded on the recording media. Theinkset or ink cartridge of the present invention is preferably used withthis recording method.

A third method is a method of recording an image on a recording media bysimultaneously applying pressure and a printing information signal to aink solution using a piezoelectric element, and spraying the inkdroplets from the nozzle towards the recording media. The inkset or inkcartridge of the present invention is preferably used with thisrecording method.

A fourth method is a method of recording an image on recording media byheating and causing the ink solution to bubble using ultrafineelectrodes in accordance with printing signal information, and thenspraying the ink from the nozzle toward the recording media by theexpansion of the bubbles. The inkset or ink cartridge of the presentinvention is preferably used with this recording method.

The inkset or the ink cartridge of the present invention preferably usesan ink composition that is used when recording an image on a recordingmedia using an image recording method according to an inkjet recordingsystem that is included in the aforementioned four methods. Recordedmatter that records an image using the inkset or ink cartridge of thepresent invention will have excellent image quality, and thelightfastness, ozonefastness, and humidityfastness will be excellent.

EXAMPLES

The present invention will be described below more specifically based onexamples, but the present invention is not restricted to the followingexamples.

Preparation of Each Ink Composition

Each of the ink compositions was obtained by blending the variouscomponents based on the formulations shown in the following Table 2,mixing for 30 minutes at room temperature, and then filtering thesolution obtained through a membrane filter with a mesh size of 1.0 μm.Note, in Table 2, the values for each component are expressed as weight% of each component based on 100% of the mass of the ink composition,and the amount of water is shown as “remainder”, meaning the amount ofwater that combined with the other components besides water will total100%.

TABLE 2 C- C- C- C- M- M- M- M- M- M- M- Y- Y- Y- Y- LC- LC- 01 02 11 1201 02 03 11 12 13 14 01 11 12 13 01 11 Cyan Dye 1 5 5 1.4 Cyan Dye 2C.I. Direct Blue 199 3.5 5 1 Magenta Dye 1 5 5 5 3 Magenta Dye 2 1Magenta Dye 3 3.5 1 1 2 Magenta Dye 4 5.5 C.I. Direct Red 227 3 YellowDye 1 5 4 3 Yellow Dye 2 1 2 Yellow Dye 3 C.I. Direct Yellow 3 173 C.I.Direct Yellow 0.8 86 Black Dye 1 Black Dye 2 C.I. Direct Black 195Glycerin 10 5 10 5 10 9 10 10 9 8 8 10 10 10 10 10 10 Triethylene glycol8 14 8 14 6 6 6 6 6 6 6 10 10 10 10 10 10 1,2-hexanediol 1 1 2 4 TEGmBE10 9 10 9 10 9 10 10 9 9 9 5 10 10 10 10 10 DEGmBE 5 Olfin E1010 (*1) 11 1 1 Surfinol 104PG50 (*2) 1 1 1 1 1 1 1 1 1 1 1 1 1 Surfinol MD20 (*2)0.2 0.2 2-pyrollidone 2 2 2 2 2 2 2 2 Urea 5 5 5 3 3 Triethanolamine 0.50.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.1 0.1 0.1 0.5 0.5 LiOHmonohydrate 0.7 0.7 2-nathoic acid 2 2 Sodium 1,5-naphthalenedisulfonateCompound 1 1 2 EDTA 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.020.02 0.02 0.02 0.02 0.02 0.02 0.02 Benotriazole 0.01 0.01 0.01 0.01 0.010.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 Proxel XL-2(*3) 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3Water Bal. Bal. Bal. Bal. Bal Bal. Bal. Bal. Bal. Bal. Bal. Bal. Bal.Bal. Bal. Bal. Bal. LC- LC- LC- LM- LM- LM- LM- LM- LM- LM- K- K- K- K-12 13 14 01 02 03 11 12 13 14 01 11 12 13 Cyan Dye 1 1.4 Cyan Dye 2 1.71.7 C.I. Direct Blue 199 Magenta Dye 1 0.9 0.9 0.9 0.5 Magenta Dye 2 10.6 Magenta Dye 3 0.6 0.6 0.8 Magenta Dye 4 2 C.I. Direct Red 227 1Yellow Dye 1 Yellow Dye 2 Yellow Dye 3 1 C.I. Direct Yellow 173 C.I.Direct Yellow 0.4 86 Black Dye 1 6 3 3 Black Dye 2 3 3 C.I. Direct Black6 195 Glycerin 10 10 10 10 10 10 10 10 10 10 9 9 9 9 Triethylene glycol7 10 8 10 9 9 9 9 8 7 2 2 2 2 1,2-hexanediol 2 2 2 TEGmBE 10 10 10 10 1010 10 10 10 10 8 8 8 DEGmBE 10 Olfin E1010 (*1) 1 1 1 1 1 1 1 1 1 1Surfinol 104PG50 (*2) 1 1 1 1 Surfinol MD20 (*2) 0.2 0.2 2-pyrollidone 22 2 2 2 2 2 2 2 2 3 3 3 3 Urea 3 3 3 3 3 3 3 3 3 3 Triethanolamine 0.90.5 0.9 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 LiOH monohydrate2-nathoic acid Sodium 4 3 1,5-naphthalenedisulfonate Compound 1 1 1.5EDTA 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.05 0.05 0.050.05 Benotriazole 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.010.01 0.01 0.01 Proxel XL-2 (*3) 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.30.3 0.3 0.3 0.3 Water Bal. Bal. Bal. Bal. Bal. Bal. Bal. Bal. Bal. Bal.Bal. Bal. Bal. Bal. (*1) Product of Nissin Chemical Industry Co., Ltd.(*2) Product of Air Products and Chemicals, Inc. (*3) Product of ArchChemicals Japan Units: weight %

Furthermore, in Table 2, C represents cyan ink composition, M representsmagenta ink composition, Y represents yellow ink composition, LCrepresents light cyan ink composition, LM represents light magenta inkcomposition, and K represents black ink composition.

In Table 2, Cyan Dye 1 and 2 are examples of the compound expressed byformula C-1, and is the compound expressed by formula A:

and Z1 through Z4 in Cyan Dye 1 and 2 are as shown below in Table 3.

TABLE 3 Z1 Z2 Z3 Z4 Cyan —(CH₂)₃SO₃Li —(CH₂)₃SO₃Li —(CH₂)₃SO₃Li—(CH₂)₃SO₂NHCH₂CH(OH)CH₃ Dye 1 Cyan —(CH₂)₃SO₃Li—(CH₂)₃SO₂NHCH₂CH(OH)CH₃ —(CH₂)₃SO₃Li —(CH₂)₃SO₂NHCH₂CH(OH)CH₃ Dye 2

C. I. Direct Blue 199 was used as the cyan dye in addition to thecompound expressed by formula C-1 which is the cyan dye according to theinvention.

In Table 2, Magenta Dye 1 is an example of a compound expressed byformula M-2, and is the compound expressed by formula B:

Note, in formula B, M represents NH₄ or Na, and the molar ratio ofNH₄:Na=1:1.

Furthermore, Magenta Dye 2 is an example of a compound expressed byformula M-1, and is the compound expressed by formula C:

and R₁ through R₄ in Magenta Dye 2 correspond to the groups shown below.

TABLE 4 R₁ R₂ R₃ R₄

Furthermore, Magenta Dye 3 is an example of a compound expressed byformula M-4, and is the compound expressed by formula D:

In addition, the magenta dyes that were used other than the compoundexpressed by formulas M-1 and M-2 which are the magenta dyes accordingto the present invention were C. I. Direct Red 227 and the Magenta dye 4expressed by formula E.

Note, in formula E, M represents NH₄ or Na, and the molar ratio ofNH₄:Na=1:1.

In Table 2, Yellow Dye 1 is an example of a compound expressed byformula Y-2, and is the compound expressed by formula F:

Furthermore, Yellow Dye 2 is an example of a compound expressed byformula Y-3, and is the compound expressed by formula G:

wherein M represents lithium or sodium, and the molar ratio ofLi:Na=4:1.

In addition, the yellow dyes that were used other than the compoundexpressed by formula Y-1 which is the yellow dye according to thepresent invention were C. I. Direct Yellow 173, and C. I. Direct Yellow86.

In Table 2, Black Dye 1 is an example of a compound expressed by formulaBk-1, and is the compound expressed by formula H:

A₁-N═N-A₂-N═N-A₃   (H)

and A₁ through A3 in Black Dye 1 correspond to the groups shown below.

TABLE 5 A₁ A₂ A₃

Furthermore, Black Dye 2 is an example of a compound expressed byformula Bk-7, and is the compound expressed by formula I:

wherein M represents either lithium or sodium. However, not all cases ofM are sodium.

Furthermore, the black dyes that were used other than the compoundsexpressed by formulas Bk-1 and Bk-7 which are the black dyes accordingto an exemplary embodiment of the present invention, were C. I. DirectBlack 195.

In addition, dyes for color matching the black ink composition includeC. I. Direct Yellow 86 and Yellow dye 3 which is the compound expressedby formula J (corresponding to the compound shown in formula Adj-1-1):

Furthermore, the betaine-based surfactant used in the magenta inkcomposition in the inkset according to the exemplary embodiment of thepresent invention contains compound 1 expressed by formula K:

(Comparable to the compound expressed by formula b-3).

In addition, the aromatic compound with a sulfonate group that is usedin the light cyan ink composition and the inkset according to anexemplary embodiment of the invention contains sodium1,5-naphthalenedisulfonate.

Next, each of the inksets from Example 1 through 8 and ComparativeExamples 1 through 8 were prepared using each of the ink compositionsprepared in the combinations shown in Table 6. Note, in the table, lightmagenta refers to the light magenta composition, and light cyan refersto the light cyan composition.

TABLE 6 Light Light Cyan Magenta Yellow Magenta Cyan Black Example 1C-11 M-11 Y-11 LM-11 LC-11 — Example 2 C-11 M-12 Y-13 LM-12 LC-13 —Example 3 C-12 M-13 Y-12 LM-13 LC-12 — Example 4 C-12 M-14 Y-11 LM-14LC-14 — Example 5 C-12 M-13 Y-12 LM-13 LC-13 K-12 Example 6 C-12 M-13Y-12 LM-13 LC-14 K-13 Example 7 C-12 M-14 Y-11 LM-14 LC-14 K-11 Example8 C-12 M-13 Y-11 LM-13 LC-14 K-13 Comparative C-01 M-01 Y-01 LM-01 LC-01— Example 1 Comparative C-02 M-11 Y-11 LM-11 LC-01 — Example 2Comparative C-11 M-01 Y-11 LM-01 LC-11 — Example 3 Comparative C-12 M-12Y-01 LM-12 LC-11 — Example 4 Comparative C-12 M-03 Y-01 LM-02 LC-11 —Example 5 Comparative C-12 M-02 Y-12 LM-03 LC-14 — Example 6 ComparativeC-02 M-02 Y-01 LM-03 LC-01 K-01 Example 7 Comparative C-12 M-12 Y-01LM-02 LC-02 K-12 Example 8

Recorded matter was prepared by printing a filled image consisting ofyellow, magenta, cyan, and black (However black was only included forthe inksets which include black.) adjusted so that the optical density(OD) of each color was between 0.9 and 1.1, on special inkjet recordingmedia <photograph paper (glossy): part number KA42OPSK; product name,manufactured by Seiko Epson Corp.> using the inkset shown in Table 6 andan inkjet printer PM-G820 (registered trademark) (product name,manufactured by Seiko Epson Corp.). The following ozonefastness test wasperformed on the printed matter obtained.

Ozonefastness Test Method

The recorded matter was exposed to ozone at a concentration of 20 ppm at24° C. and 60% RH using an ozone weather-o-meter model OMS-H (productname, manufactured by Suga Test Instruments Co., Ltd.). The OD of eachcolor recorded on the printed matter was measured at set time intervalsfrom the start of exposure using a density meter (Spectrolino(registered trademark), manufactured by Gretag Corp.). The measurementconditions were a light source of D50, and a viewing angle of 2°.Furthermore, measurements were taken using a red filter for cyan, agreen filter for magenta, and a blue filter for yellow, and no filterwas used for black. The residual optical density (ROD) was determinedfrom the results obtained using the following equation:

ROD(%)=(D/D ₀)×100

(In the formula, D is the OD value after exposure testing and D₀ is theOD value before exposure testing.)

Furthermore, based on the results of the above test, the ozonefastnessfor each color recorded on the recorded matter was ranked A to F usingthe following judgment criteria.

Judgment Criteria

-   Level A: ROD does not drop below 70% after 40 hours.-   Level B: ROD drops to 70% after 32 hours but less than 40 hours.-   Rank C: ROD drops to 70% after 24 hours but less than or equal to 32    hours.-   Level D: ROD drops to 70% after 16 hours but less than 24 hours.-   Level E: ROD drops to 70% after 8 hours but less than 16 hours.-   Level F: ROD drops to 70% in less than 8 hours.

With the present invention, the reduction in the ROD of the recordedmatter was minimal even after long term exposure to ozone. The resultsobtained are shown in Table 7.

From the results of the ozonefastness test for each color, theozonefastness of each of the color sets was ranked using the followingjudgment criteria.

Judgment Criteria

-   Rank A: The ozonefastness test results were at Rank A for all three    colors (four colors if black is included).-   Rank B: One or more of the 3 color inks (four colors inks if black    is included) had ozonefastness test results at Rank B.-   Rank C: One or more of the 3 color inks (four colors inks if black    is included) had ozonefastness test results at Rank C.-   Rank D: One or more of the 3 color inks (four colors inks if black    is included) had ozonefastness test results at Rank D.-   Rank E: One or more of the 3 color inks (four colors inks if black    is included) had ozonefastness test results at Rank E.-   Rank F: One or more of the 3 color inks (four colors inks if black    is included) had ozonefastness test results at Rank F.

In this evaluation, rank A was the best, followed by rank B. The resultsobtained are shown as the “Ozonefastness of Inkset” in Table 7.

Furthermore, the difference (balance) in the changes of ROD for eachcolor of the printed matter caused by exposure to ozone was evaluatedfor each recorded matter using the following judgment criteria for eachinkset.

Judgment Criteria

-   Rank A: The difference between the maximum value and the minimum    value for the ROD of each color (hereinafter referred to as the “ROD    difference” in the discussion of this evaluation method) was less    than 15 points even after 40 hours from the start of testing.-   Rank B: The ROD difference was 15 points between 32 hours and 40    hours after the start of testing.-   Rank C: The ROD difference was 15 points between 24 hours and 32    hours after the start of testing.-   Rank D: The ROD difference was 15 points between 16 hours and 24    hours after the start of testing.-   Rank E: The ROD difference was 15 points between 8 hours and 16    hours after the start of testing.-   Rank F: The ROD difference was 15 points within 8 hours from the    start of testing.

In this evaluation, recorded matter which had a small ROD difference wassuperior. The evaluation results obtained are shown as “Ozonefastness(Color Balance) of the Inkset” in Table 7.

TABLE 7 Ozonefastness of Ozonefastness of Individual Colors InksetMagen- Color Cyan ta Yellow Black Ozonefastness Balance Example 1 D D A— D D Example 2 C C C — C A Example 3 B B B — B A Example 4 A A A — A AExample 5 C B B B C B Example 6 A B B B B B Example 7 A A A A A AExample 8 A B A B B B Comparative F F A — F F Example 1 Comparative F DA — F F Example 2 Comparative D F A — F F Example 3 Comparative D C A —D D Example 4 Comparative D D A — D D Example 5 Comparative A E B — E EExample 6 Comparative F E A F F F Example 7 Comparative F D A B F FExample 8

Fluorescent Lightfastness Test Method

The recorded matter used for the ozonefastness test was re-created forthe inkset shown in Table 6, and the recorded matter was exposed using afluorescent lightfastness tester model SFT-III (product name,manufactured by Suga Test Instruments Co. Ltd.) at 24° C. and 60% RHwith an intensity of 70,000 lux. The OD of each color recorded on theprinted matter was measured at set time intervals from the start ofexposure using a temperature meter (Spectrolino (registered trademark),manufactured by Gretag Corp.). The measurement conditions were a lightsource of D50, and a viewing angle of 2°. Furthermore, measurements weretaken using a red filter for cyan, a green filter for magenta, and ablue filter for yellow, and no filter was used for black. The residualoptical density (ROD) was determined from the results obtained using thefollowing equation:

ROD(%)=(D/D ₀)×100

(In the formula, D is the OD value after exposure testing and D₀ is theOD value before exposure testing.)

Furthermore, based on the results of the above test, the lightfastnessfor each color recorded on the recorded matter was ranked A to F usingthe following judgment criteria.

Judgment Criteria

-   Level A: ROD does not drop below 70% after 70 days.-   Level B: ROD drops to 70% after 50 days but less than or equal to 70    days.-   Level C: ROD drops to 70% after 30 days but less than or equal to 50    days.-   Level D: ROD drops to 70% after 20 days but less than or equal to 30    days.-   Level E: ROD drops to 70% after 10 days but less than or equal to 20    days.-   Level F: ROD drops to 70% in less than 10 days.

With the present invention, the reduction in the ROD of the recordedmatter was minimal even after long term exposure to fluorescent light.The results obtained are shown in Table 8.

From the results of the fluorescent lightfastness test for each color,the lightfastness of each of the color sets was ranked using thefollowing judgment criteria.

Judgment Criteria

-   Level A: The lightfastness test results were at Level A for all    three colors (four colors if black is included).-   Rank B: One or more of the 3 color inks (four colors inks if black    is included) had lightfastness test results at Rank B.-   Rank C: One or more of the 3 color inks (four colors inks if black    is included) had lightfastness test results at Rank C.-   Rank D: One or more of the 3 color inks (four colors inks if black    is included) had lightfastness test results at Rank D.-   Rank E: One or more of the 3 color inks (four colors inks if black    is included) had lightfastness test results at Rank E.-   Rank F: One or more of the 3 color inks (four colors inks if black    is included) had lightfastness test results at Rank F.

In this evaluation, rank A was the best, followed by rank B. The resultsobtained are shown as the “Lightfastness of Inkset(Lightfastness)” inTable 8.

Furthermore, the difference (balance) in the changes of ROD for eachcolor of the printed matter caused by exposure to fluorescent light wasevaluated for each recorded matter using the following judgment criteriafor each inkset.

Judgment Criteria

-   Rank A: The difference between the maximum value and the minimum    value for the ROD of each color (hereinafter referred to as the “ROD    difference” in the discussion of this evaluation method) was less    than 15 points even after 70 days from the start of testing.-   Rank B: The ROD difference was 15 points between 50 days and 70 days    after the start of testing.-   Rank C: The ROD difference was 15 points between 30 days and 50 days    after the start of testing.-   Rank D: The ROD difference was 15 points between 20 days and 30 days    after the start of testing.-   Rank E: The ROD difference was 15 points between 10 days and 20 days    after the start of testing.-   Rank F: The ROD difference was 15 points within 10 days from the    start of testing.

In this evaluation, recorded matter which had a small ROD difference wassuperior. The evaluation results obtained are shown as “Lightfastness(Color Balance) of the Inkset” in Table 8.

TABLE 8 Lightfastness of Lightfastness of Inkset Individual Colors ColorCyan Magenta Yellow Black Lightfastness Balance Example 1 A C A — C CExample 2 A C C — C C Example 3 A B B — B B Example 4 A A A — A AExample 5 A B B B B B Example 6 A B B B B B Example 7 A A A A A AExample 8 A B A B B B Comparative A F E — F F Example 1 Comparative A CA — C C Example 2 Comparative A F A — F F Example 3 Comparative A C E —E E Example 4 Comparative A D E — E E Example 5 Comparative A C B — C CExample 6 Comparative A C E E E E Example 7 Comparative A D E B E EExample 8

Humidityfastness Evaluation

Colored text and white text on color (text formed in white on a filledimage of each color) for cyan, magenta, yellow, and black (However blackis only included for inksets which include black.) was printed at themaximum density of each color for the inksets of examples 1 through 8and comparative examples 1 through 8 on special inkjet recording media<photograph paper (glossy): part number KA42OPSK; product name,manufactured by Seiko Epson Corp.>, and dried for 24 hours at 24° C. and50% RH. Next the recorded media was placed in an environment away fromdirect sunlight at 40° C. and 85% RH. After setting for 4 days in thisenvironment, the level of bleeding of the text and the white text werevisually observed, and an evaluation was made based on the followingjudgment criteria.

Judgment Criteria

-   Rank A: Absolutely no bleeding of the colorant was observed.-   Rank B: Almost no bleeding of the colorant was observed.-   Rank C: Slight bleeding of the colorant was observed, and the    contour of the text was slightly damaged.-   Rank D: Bleeding of the colorant was observed, and the contour of    the text was damaged.-   Rank E: Bleeding of the colorant was observed, the text was thicker,    and the white on color text was generally stained.-   Rank F: Severe bleeding of the colorant was observed, and both the    text and the white on color text were illegible.

The results obtained are shown in Table 9 as “humidityfastness”.

TABLE 9 Humidityfastness of Individual Colors Humidityfastness of CyanMagenta Yellow Black Inkset Example 1 A B A — B Example 2 A B B — BExample 3 A A A — A Example 4 A B A — B Example 5 A A A A A Example 6 AA A A A Example 7 A B A A B Example 8 A A A A A Comparative A A B — BExample 1 Comparative A B A — B Example 2 Comparative A A A — A Example3 Comparative A B B — B Example 4 Comparative A E B — E Example 5Comparative A F A — F Example 6 Comparative A F B C F Example 7Comparative A E B A E Example 8

Evaluation of Reflective Optical Density for Black Ink on Various Media

Monochrome printing was performed while changing the weight of printingink for each of the black inks in the inkset of examples 5 to 8 usinginkjet special recording media “photographic paper (glossy): productnumber KA420PSK; product name, manufactured by Seiko Epson Corp.”, aswell as “photomatte paper: product number KA420PM; product name,manufactured by Seiko Epson Corp.” and normal paper “Xerox4024; productname, manufactured by Xerox Corp.” The reflected optical density of theprinted matter was measured using a density meter (Spectrolino(registered trademark), manufactured by Gretag Corp.). The measurementconditions were a light source of D50, and a viewing angle of 2° with nofilter. The maximum value for the reflective optical density wasdetermined. The results obtained are shown in Table 10 as the Evaluationof Reflective Optical Density of Black Ink and Various Media.

TABLE 10 Maximum Reflective Optical Density of Various Black Inks onDifferent Media Photographic paper (glossy) Photomatte paper Xerox-4024Example 5 2.45 1.75 1.25 Example 6 2.45 1.75 1.25 Example 7 2.45 1.651.2 Example 8 2.45 1.75 1.25

The results obtained for the 3 types and 5 items of evaluation, namelyozonefastness, lightfastness, and humidityfastness are shown again inTable 11 and a ranking of the overall characteristics was made.

TABLE 11 Ozonefastness of Lightfastness of Inkset Inkset Color ColorHumidityfastness Ozonefastness Balance Lightfastness Balance of InksetOverall Example 1 D D C C B C Example 2 C A C C B B Example 3 B A B B AB Example 4 A A A A B A Example 5 C B B B A B Example 6 B B B B A BExample 7 A A A A B A Example 8 B B B B A B Comparative F F F F B EExample 1 Comparative F F C C B D Example 2 Comparative F F F F A EExample 3 Comparative D D E E B D Example 4 Comparative D D E E E EExample 5 Comparative E E C C F D Example 6 Comparative F F E E F FExample 7 Comparative F F E E E E Example 8

A ranking of A through F was made for the overall evaluation, and a rankof A was most superior, followed by a superior rank of B. Furthermore, arank of F indicated the worst characteristics.

The present invention has a possibility of industrial application as aninkset that can record an image with excellent lightfastness,ozonefastness, and humidityfastness on a recording medium, as well as anink cartridge, inkjet recording method, and recorded matter.

1. An inkset comprising at least a yellow ink composition, two types of magenta ink compositions of different color density, and a cyan ink composition: the magenta ink composition containing as a colorant at least one type of compound expressed by the following formula M-1, and at least one type of compound expressed by the following formula M-2,

(where in formula M-1, A represents a residue of a five membered heterocyclic diazo component A-NH₂. B¹ and B² each represent —CR¹═ or —CR²═, or either one represents a nitrogen atom while the other represent either —CR¹═ or —CR²═. R⁵ and R⁶ each independently represent a hydrogen atom, an aliphatic group, an aromatic group, a heterocyclic group, an acyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, a carbamoyl group, an alkylsulfonyl group, an arylsulfonyl group, or a sufamoyl group. Each group may also have a substituent group. G, R1, and R2 each independently represent a hydrogen atom, a halogen atom, an aliphatic group, an aromatic group, a heterocyclic group, a cyano group, a carboxyl group, a carbamoyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, an acyl group, a hydroxyl group, an alkoxy group, an aryloxy group, a silyloxy group, an acyloxy group, a carbamoyloxy group, a heterocycloxygroup, an alkoxycarbonyloxy group, an aryloxycarbonyloxy group, an amino group substituted with an alkyl group, aryl group, or heterocyclic group, an acylamino group, a ureido group, a sulfamoylamino group, alkoxycarbonylamino group, an aryloxycarbonylamino group, an alkyl or arylsulfonylamino group, an aryloxycarbonylamino group, a nitro group, an alkyl or arylthio group, an alkyl or arylsulfonyl group, an alkyl or arylsulfinyl group, a sulfamoyl group, a sulfo group, or a heterocyclothio group. Each group may also contain other substituent groups. Furthermore, R¹ or R⁵or R¹ and R⁵ bonded together can form a 5 or 6 membered ring.)

(where in formula M-2, M represents a hydrogen atom, ammonium group, or alkali metal atom, X represents a diaminoalkylene group, and n is either 1 or 2.); the yellow ink composition containing as a colorant at least one type of compound expressed by the following formula Y-1

(where in the formula, X₁, X₂, Y₁, and Y₂ represent a hydrogen atom or a cyano group, Z₁ and Z₂ represent a substituent group with an aromatic ring, R₁ and R₂ represent alkyl groups, and M represents a metal atom.); the cyan ink composition containing as a cyan dye at least one type of compound selected from the compounds or salt thereof expressed by the following formula C-1

(where in formula C-1, X₁, X₂, X₃, and X₄ independently represent either —SO-Z or—SO₂-Z. Herein, Z independently represents a substituted or unsubstituted alkyl group, a substituted or unsubstituted cycloalkyl groups, a substituted or unsubstituted alkenyl group, a substituted or unsubstituted aralkyl group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted heterocyclic group. Y₁, Y₂, Y₃, and Y₄ independently represent a hydrogen atom, a halogen atom, an alkyl group, a cycloalkyl group, an alkenyl group, an aralkyl group, an aryl group, a heterocyclic group, a cyano group, an hydroxyl group, a nitro group, an amino group, an alkylamino group, an alkoxy group, an aryloxy group, an amido group, an arylamino group, an ureido group, a sulfamoylamino group, an alkylthio group, an arylthio group, an alkoxycarbonylamino group, a sulfonamide group, a carbamoyl group, an alkoxycarbonyl group, a heterocycloxy group, an azo group, an acyloxy group, a carbamoyloxy group, a silyloxy group, an aryloxycarbonyl group, an aryloxycarbonylamino group, an imido group, a heterocyclthio group, a phospholyl group, an acyl group, or an ionic hydrophilic group, and each of the groups may also have substituent groups. a₁ through a₄ and b₁ through b₄ represent the number of substituent groups of X₁ through X₄ and Y₁ through Y₄. Furthermore a₁ through a₄ are independently integers between 0 and 4, but are not all simultaneously
 0. b₁ through b₄ are independently integers between 0 and
 4. M represents a hydrogen atom, a metal atom or oxide, a hydroxide, or a halide thereof. However, at least one of X₁, X₂, X₃, X₄, Y₁, Y₂, Y₃, and Y₄ is an ionic hydrophilic group or a group which has an ionic hydrophilic group as a substituent group.).
 2. The inkset according to claim 1, wherein the compound expressed by formula M-1 which is a colorant included in the magenta ink composition is a compound expressed by formula M-3: C5

(In formula M-3, R₁ through R₅ represent a hydrogen atom, alkyl group, sulfo group, or salt thereof, and when R₁ and R₅ are independently both alkyl groups, the total number of carbons in the alkyl groups is 3 or more, and substituent groups may also be present. X represents a hydrogen atom, an aliphatic group, an aromatic group, or a heterocyclic group, and Y and Z each independently represent a hydrogen atom, an aliphatic group, an aromatic group, a heterocyclic group, an acyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, a carbamoyl group, an alkylsulfonyl group, an arylsulfonyl group, or a sulfamoyl group. Each group may also have a substituent group.).
 3. The inkset according to claim 1, wherein the compound expressed by formula M-3 is a compound expressed by formula M-4:

(In formula M-4, R₁ through R₁₀ represent a hydrogen atom, alkyl group, sulfo group, or salt thereof, and when (R₁ and R₅) and (R₆ and R₁₀) are independently both alkyl groups, the total number of carbons in the alkyl groups is 3 or more, and substituent groups may also be present. Furthermore, M represents a hydrogen atom or an alkali metal atom.).
 4. The inkset according to claim 1, wherein the n represents 2 in the compound expressed by formula M-2 which is a colorant contained in the magenta ink composition.
 5. The inkset according to claim 1, wherein of the two types of magenta ink compositions of different color density, the magenta ink composition of lower color density contains as a colorant at least one type of compound expressed by formula M-1 and at least one type of compound expressed by formula M-2, and the total amount of the colorants is such that the amount of at least one type of compound expressed by formula M-1 is between 0.2 and 1.0 wt %, and the amount of at least one type of compound expressed by formula M-2 is between 0.3 and 1.5 wt %, based on the total weight of magenta ink composition of lower color density.
 6. The inkset according to claim 1, wherein of the two types of magenta ink compositions of different color density, the magenta ink composition of higher color density contains as a colorant at least one type of compound expressed by formula M-1 and at least one type of compound expressed by formula M-2, and the total amount of the colorants is such that the amount of at least one type of compound expressed by formula M-1 is between 0.6 and 2.5 wt %, and the amount of at least one type of compound expressed by formula M-2 is between 1.5 and 7.0 wt %, based on the total weight of magenta ink composition of higher color density.
 7. The inkset according to claim 1, wherein in the magenta ink composition of lower color density of the two types of magenta ink composition of different color density, the content weight ratio of the compound expressed by formula M-1 and the compound expressed by formula M-2 is in a range between 2:1 and 1:2.
 8. The inkset according to claim 1, wherein in the magenta ink composition of higher color density of the two types of magenta ink composition of different color density, the content weight ratio of the compound expressed by formula M-1 and the compound expressed by formula M-2 is in a range between 1:1 and 1:8.
 9. The inkset according to claim 1, containing a betaine-based surfactant expressed by the following formula b-1 in the magenta ink composition: (R)p-N-[L-(COOM)q]r   (b-1) (In formula b-1, R represents a hydrogen atom, an alkyl group, an aryl group, or a heterocyclic group. L represents a bonding group with a valence of two or higher. M represents a hydrogen atom, an alkali metal atom, an ammonium group, a protonated organic amine or nitrogen containing heterocyclic group, or a quaternary ammonium ion group, and represents a group that does not exist as a cation if M is a counter ion for the ammonium ion containing nitrogen atom shown in formula b-1. q represents an integer 1 or greater, and r represent an integer between 1 and
 4. p represents an integer between 0 and 4, and p+r is either 3 or
 4. If p+r is 4, N represents a nitrogen atom that forms a quaternary amine. If p is 2 or higher, R may be the same or may be different. If q is 2 or higher, COOM may be the same or may be different. If r is 2 or higher, L-(COOM)q may be the same or may be different.).
 10. The inkset according to claim 9, wherein the betaine-based surfactant expressed by formula b-1 is a compound expressed by formula b-2:

(In formula b-2. R1 through R3 represent alkyl groups having 1 to 20 carbons, and X represents a bonding group with a valence of 2.).
 11. The inkset according to claim 10, wherein the compound expressed by formula b-2 is a compound expressed by formula b-3.


12. The inkset according to claim 9, wherein the content weight ratio of the compound expressed by formula M-1 and the betaine surfactant expressed by formula b-1 is in a range between 1:3 and 3:1.
 13. The inkset according to claim 1, wherein the compound expressed by formula Y-1 which is contained in the yellow ink composition as a colorant is a compound expressed by the following formula Y-2:

(in the formula, X₁, X₂, Y₁, and Y₂ represent a hydrogen atom or a cyano group, W₁ through W₅ and W₁₁ through W₁₅ each represent a hydrogen atom, or a carboxyl group or salt thereof, M represents a metal atom, and t-Bu represent a tertiary butyl group).
 14. The inkset according to claim 1, wherein the yellow ink composition further contains as a colorant at least one type of compound expressed by the following formula Y-3:

(In the formula, R represents a methoxy group or a methyl group, and A represents 1,5-disulfonaphtho-3-yl or 1,5,7-trisulfonaphtho-2-yl.).
 15. The inkset according to claim 1, wherein the total amount of colorant in the yellow ink composition is between 1 and 7 wt % based on the total weight of the yellow ink composition.
 16. The inkset according to claim 1, wherein in the compound expressed by formula C-1 that is contained as the cyan dye in the cyan ink composition, M represents a copper atom, X₁, X₂, X₃, and X₄ represent —SO₂Z, Z represents R⁵ (R⁵ represents —(CH₂)₃SO₃M² where M² represents an alkali metal atom) or R⁶ (R⁶ represents —(CH₂)₃SO₂NHCH₂CH(OH)CH₃), Y₁, Y₂, Y₃, and Y₄ are hydrogen atoms, a₁, a₂, a₃, and a₄ are either 0 or 1, two or more of a₁, a₂, a₃ and a₄ are 1, and b₁, b₂, b₃, and b₄ are integers such that the sum of each of them with the corresponding a₁, a₂, a₃, and a₄ is
 4. 17. The inkset according to claim 16, wherein M² represents lithium.
 18. The inkset according to claim 16, wherein for the cyan dye, Z in the compound expressed by formula C-1 independently represents a blend consisting of tetrasulfonates, trisulfonates, and disulfonates selected from R⁵ or R⁶, and the molar ratio of R⁵ and R⁶ contained in all of the cyan dye R⁵/R⁶ is between 2/2 and 4/0.
 19. The inkset according to claim 1, wherein at least one type of compound selected from the group consisting of compounds or salts thereof expressed by formula C-1 is contained as a colorant in the cyan ink composition, and the total amount of colorant is between 1.0 and 10 wt % based on the total weight of the cyan ink composition.
 20. The inkset according to claim 1, having two types of cyan ink compositions of different color density as the cyan ink composition, and the cyan ink compositions contain at least one type of compound selected from a group consisting of the compounds expressed by formula C-1 and salts thereof.
 21. The inkset according to claim 20, wherein of the two types of cyan ink compositions of different color density, the cyan ink composition of lower color density contains as a colorant at least one type of a compound selected from a group consisting of the compounds expressed by formula C-1 and salts thereof, and the total amount of the colorant is between 0.4 and 3.0 wt %, based on the total weight of the cyan ink of lower color density.
 22. The inkset according to claim 20, wherein of the two types of cyan ink compositions of different color density, the cyan ink composition of higher color density contains as a colorant at least one type of a compound selected from a group consisting of the compounds expressed by formula C-1 and salts thereof, and the total amount of the colorant is between 2.0 and 10.0 wt %, based on the total weight of the cyan ink of higher color density.
 23. The inkset according to claim 20, wherein in the two types of cyan ink compositions of different color density, the ratio of the concentration (wt %) of colorant included in the cyan ink composition of lower color density and the concentration (wt %) of colorant included in the cyan ink composition of higher color density is in a range between 1:2 and 1:8.
 24. The inkset according to claim 20, wherein both of the two types of cyan ink compositions of different color density contain as a colorant at least one type of compound selected from a group consisting of the compounds expressed by formula C1 and salts thereof, and in the compound expressed by formula C1 that is included in the cyan ink composition of lower color density, Z independently represents a blend consisting of a disulfonate, a trisulfonate, and a tetrasulfonate selected from R⁵ and R⁶, and the molar ratio of the R⁵ and R⁶ contained in all of the cyan dye R⁵/R⁶ is between 1/3 and 3/1, while in the compound expressed by formula C1 that is included in the cyan ink composition of higher color density, Z independently represents a blend consisting of a disulfonate, a trisulfonate, and a tetrasulfonate selected from R⁵ and R⁶, and the molar ratio of the R⁵ and R⁶ contained in all of the cyan dye R⁵/R⁶ is between 2/2 and 4/0.
 25. The inkset according to claim 20, wherein of the two types of cyan ink compositions of different color density, the cyan ink composition of lower color density further contains an aromatic compound having a sulfo group as expressed by the following general formula (a) and/or (b), and/or a salt thereof:

(wherein M¹ represents a hydrogen atom, or a counter ion that forms a salt, X represents an integer of 1 or higher, R¹ and R² each represent a hydrogen atom, alkyl group having 1 to 6 carbons, or an alkoxy group having 1 to 6 carbons, where R¹ and R² may be the same or different.)

(wherein M² represents a hydrogen atom, or a counter ion that forms a salt, Y represents an integer of 1 or higher, R³ and R⁴ each represent a hydrogen atom, alkyl group having 1 to 6 carbons, or an alkoxy group having 1 to 6 carbons, where R³ and R⁴ may be the same or different.).
 26. The inkset according to claim 25, wherein the salt of the aromatic compound having a sulfo group expressed by general formula (a) and/or (b) is a lithium salt.
 27. The inkset according to claim 25, wherein for the cyan ink composition of lower color density, the content weight ratio of the cyan dye and the aromatic compound having a sulfo group and/or salt thereof is in a range between 1:1 and 1:5.
 28. The inkset according to claim 20, wherein of the two types of cyan ink compositions of different color density, the cyan ink composition of higher color density contains at least one type of compound selected from the group consisting of naphthalene based aromatic compounds having a carboxyl group in the second position, or salts thereof.
 29. The inkset according to claim 28, wherein the salt of the naphthalene based aromatic compound having a carboxyl group in the second position is a lithium salt.
 30. The inkset according to claim 1, further comprising a black ink composition.
 31. The inkset according to claim 30, wherein the black ink composition contains a colorant expressed by the following formula Bk-1: A₁-N═N-A₂-N═N-A₃   (Bk-1) (in formula Bk-1, A₁ represents a substituent group expressed by the following formula Bk-2 or Bk-3, A₂ represents a substituent group expressed by the following formula Bk-4 or Bk-5, and A₃ represents a substituent group expressed by the following formula Bk-6)

(where in formula Bk-2, M represents either lithium or sodium.)

(where in formula Bk-3, M represents either lithium or sodium.)

(where in formula Bk-6, M represents either lithium or sodium.).
 32. The inkset according to claim 30, wherein the black ink composition further contains a colorant expressed by the following formula Bk-7:

(in formula Bk-7, R₁ represents a halogen atom, H, SO₃M, or COOM, R₂ and R₃ independently represent H, SO₃M, or COOM, and M represents either lithium or sodium. However, R₂ and R₃ are not both H.).
 33. The inkset according to claim 32, wherein the total of the amount of colorant expressed by formula Bk-1 and the amount of colorant expressed by formula Bk-7 is between 5 and 8 wt % of the black ink composition.
 34. The inkset according to claim 32, wherein the formulation weight ratio of the colorant expressed by formula Bk-1 and the colorant expressed by formula Bk-7 in the black ink composition is between 2:1 and 1:2.
 35. The inkset according to claim 30, wherein the black ink composition further contains a colorant expressed by the following formula Adj-1:

(where in the formula, M represents either lithium or sodium.).
 36. The inkset according to claim 35, wherein the colorant expressed by formula Adj-1 is a colorant expressed by the following formula Adj-1-1.


37. The inkset according to claim 30, wherein the black ink composition further contains C. I. Direct Yellow 86 as a colorant.
 38. The inkset according to claim 1, wherein the ink composition contains a nonionic surfactant.
 39. The inkset according to claim 38, wherein the nonionic surfactant is an acetylene glycol surfactant.
 40. The inkset according to claim 38, wherein the ink composition contains between 0.1 and 5 wt % of the nonionic surfactant.
 41. The inkset according to claim 1, wherein the ink composition contains a penetration enhancing agent.
 42. The inkset according to claim 41, wherein the penetration enhancing agent is a glycol ether.
 43. An ink cartridge that integrally or independently stores the inkset described in claim
 1. 44. An inkjet recording method for performing recording using the ink cartridge described in claim
 43. 45. A recorded matter recorded using the ink cartridge described in claim
 43. 